<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with WebFilings-->
<!-- -->
<linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <roleRef roleURI="http://www.costar.com/role/Acquisition" xlink:href="csgp-20131231.xsd#Acquisition" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/AcquisitionDetails" xlink:href="csgp-20131231.xsd#AcquisitionDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/AcquisitionScheduleOfAssetsAcquiredAndLiabilitiesAssumedOfLoopnetAcquisitionDetails" xlink:href="csgp-20131231.xsd#AcquisitionScheduleOfAssetsAcquiredAndLiabilitiesAssumedOfLoopnetAcquisitionDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/AcquisitionScheduleOfConsiderationPaidToAquireLoopnetDetails" xlink:href="csgp-20131231.xsd#AcquisitionScheduleOfConsiderationPaidToAquireLoopnetDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/AcquisitionTables" xlink:href="csgp-20131231.xsd#AcquisitionTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/CommitmentsAndContingencies" xlink:href="csgp-20131231.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/CommitmentsAndContingenciesDetails" xlink:href="csgp-20131231.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/CommitmentsAndContingenciesTables" xlink:href="csgp-20131231.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedBalanceSheets" xlink:href="csgp-20131231.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="csgp-20131231.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="csgp-20131231.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:href="csgp-20131231.xsd#ConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedStatementsOfOperations" xlink:href="csgp-20131231.xsd#ConsolidatedStatementsOfOperations" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:href="csgp-20131231.xsd#ConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/DocumentAndEntityInformationDocumentAndEntityInformation" xlink:href="csgp-20131231.xsd#DocumentAndEntityInformationDocumentAndEntityInformation" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/EmployeeBenefitPlans" xlink:href="csgp-20131231.xsd#EmployeeBenefitPlans" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/EmployeeBenefitPlansDetails" xlink:href="csgp-20131231.xsd#EmployeeBenefitPlansDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/EmployeeBenefitPlansTables" xlink:href="csgp-20131231.xsd#EmployeeBenefitPlansTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/FairValue" xlink:href="csgp-20131231.xsd#FairValue" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/FairValueDetails" xlink:href="csgp-20131231.xsd#FairValueDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/FairValueTables" xlink:href="csgp-20131231.xsd#FairValueTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/Goodwill" xlink:href="csgp-20131231.xsd#Goodwill" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/GoodwillDetails" xlink:href="csgp-20131231.xsd#GoodwillDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/GoodwillTables" xlink:href="csgp-20131231.xsd#GoodwillTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IncomeTaxes" xlink:href="csgp-20131231.xsd#IncomeTaxes" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IncomeTaxesDetails" xlink:href="csgp-20131231.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IncomeTaxesTables" xlink:href="csgp-20131231.xsd#IncomeTaxesTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IntangiblesAndOtherAssets" xlink:href="csgp-20131231.xsd#IntangiblesAndOtherAssets" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IntangiblesAndOtherAssetsDetails" xlink:href="csgp-20131231.xsd#IntangiblesAndOtherAssetsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/IntangiblesAndOtherAssetsTables" xlink:href="csgp-20131231.xsd#IntangiblesAndOtherAssetsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/Investments" xlink:href="csgp-20131231.xsd#Investments" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/InvestmentsAvailableForSaleSecuritiesDetails" xlink:href="csgp-20131231.xsd#InvestmentsAvailableForSaleSecuritiesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/InvestmentsDetails" xlink:href="csgp-20131231.xsd#InvestmentsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/InvestmentsTables" xlink:href="csgp-20131231.xsd#InvestmentsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/LongTermDebt" xlink:href="csgp-20131231.xsd#LongTermDebt" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/LongTermDebtDetails" xlink:href="csgp-20131231.xsd#LongTermDebtDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/LongTermDebtScheduleOfMaturitiesOfLongTermDebtDetails" xlink:href="csgp-20131231.xsd#LongTermDebtScheduleOfMaturitiesOfLongTermDebtDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/LongTermDebtTables" xlink:href="csgp-20131231.xsd#LongTermDebtTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/NetIncomePerShare" xlink:href="csgp-20131231.xsd#NetIncomePerShare" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/NetIncomePerShareDetails" xlink:href="csgp-20131231.xsd#NetIncomePerShareDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/NetIncomePerShareTables" xlink:href="csgp-20131231.xsd#NetIncomePerShareTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/Organization" xlink:href="csgp-20131231.xsd#Organization" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/OrganizationDetails" xlink:href="csgp-20131231.xsd#OrganizationDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/PropertyAndEquipment" xlink:href="csgp-20131231.xsd#PropertyAndEquipment" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/PropertyAndEquipmentDetails" xlink:href="csgp-20131231.xsd#PropertyAndEquipmentDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/PropertyAndEquipmentTables" xlink:href="csgp-20131231.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:href="csgp-20131231.xsd#ScheduleIiValuationAndQualifyingAccounts" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccountsDetails" xlink:href="csgp-20131231.xsd#ScheduleIiValuationAndQualifyingAccountsDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccountsTables" xlink:href="csgp-20131231.xsd#ScheduleIiValuationAndQualifyingAccountsTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SegmentReporting" xlink:href="csgp-20131231.xsd#SegmentReporting" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SegmentReportingDetails" xlink:href="csgp-20131231.xsd#SegmentReportingDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SegmentReportingTables" xlink:href="csgp-20131231.xsd#SegmentReportingTables" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/StockholdersEquity" xlink:href="csgp-20131231.xsd#StockholdersEquity" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/StockholdersEquityDetails" xlink:href="csgp-20131231.xsd#StockholdersEquityDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeLossNetOfTaxDetails" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeLossNetOfTaxDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesStockBasedCompensationExpenseDetails" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPoliciesStockBasedCompensationExpenseDetails" xlink:type="simple" />
  <roleRef roleURI="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="csgp-20131231.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <calculationLink xlink:role="http://www.costar.com/role/Acquisition" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/AcquisitionDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/AcquisitionScheduleOfAssetsAcquiredAndLiabilitiesAssumedOfLoopnetAcquisitionDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_10767bb4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_10767bb4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_10224c42-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_10224c42-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessCombinationRecognizedGoodwillAcquired" xlink:label="loc_csgp_BusinessCombinationRecognizedGoodwillAcquired_0f23bdba-f882-11e2-a68d-22000a9d039f" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessCombinationRecognizedGoodwillAcquired_0f23bdba-f882-11e2-a68d-22000a9d039f" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_1088a3e8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_1088a3e8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredCustomerBase" xlink:label="loc_csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredCustomerBase_9f96ef9e-2962-13b7-c7a4-2b547518232d" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredCustomerBase_9f96ef9e-2962-13b7-c7a4-2b547518232d" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredDatabaseTechnology" xlink:label="loc_csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredDatabaseTechnology_e3a22c61-b9ad-5b4a-f245-2b547065220c" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessAcquisitionPurchasePriceAllocationAcquiredDatabaseTechnology_e3a22c61-b9ad-5b4a-f245-2b547065220c" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDeferredTaxAssetsandLiabilitiesNet" xlink:label="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDeferredTaxAssetsandLiabilitiesNet_a155bf4e-f959-11e2-a68d-22000a9d039f" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedDeferredTaxAssetsandLiabilitiesNet_a155bf4e-f959-11e2-a68d-22000a9d039f" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessAcquisitionPurchasePriceAllocationOtherAssetsAndLiabilities" xlink:label="loc_csgp_BusinessAcquisitionPurchasePriceAllocationOtherAssetsAndLiabilities_d8cb5ec3-e57c-07df-f384-2b545cde9012" xlink:type="locator" />
    <calculationArc order="8" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_13b6e3b8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessAcquisitionPurchasePriceAllocationOtherAssetsAndLiabilities_d8cb5ec3-e57c-07df-f384-2b545cde9012" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/AcquisitionScheduleOfConsiderationPaidToAquireLoopnetDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_1126089a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_8ad60816-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1_1126089a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_8ad60816-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_10a2243a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1_1126089a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_10a2243a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/AcquisitionTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_80207e60-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_80207e60-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_813e614a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_813e614a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_8014ac16-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_8014ac16-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_800d5182-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_800d5182-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_8010265a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_8010265a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_800588bc-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_814b431a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_800588bc-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedBalanceSheets" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_18320242-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_18320242-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShortTermInvestments" xlink:label="loc_us-gaap_ShortTermInvestments_ac3ee1b2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ShortTermInvestments_ac3ee1b2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_05404162-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_05404162-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsNetCurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetCurrent_2af7d532-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsNetCurrent_2af7d532-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxesReceivable" xlink:label="loc_us-gaap_IncomeTaxesReceivable_6174892a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxesReceivable_6174892a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_90f899ac-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_90f899ac-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredCostsCurrent" xlink:label="loc_us-gaap_DeferredCostsCurrent_2a1ffdce-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_0d216a96-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredCostsCurrent_2a1ffdce-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermInvestments" xlink:label="loc_us-gaap_LongTermInvestments_760fe99c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermInvestments_760fe99c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_940b342e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_940b342e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_5c519906-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_Goodwill_5c519906-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_6701f814-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_6701f814-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DepositsAssetsNoncurrent" xlink:label="loc_us-gaap_DepositsAssetsNoncurrent_325d494c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DepositsAssetsNoncurrent_325d494c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredCosts" xlink:label="loc_us-gaap_DeferredCosts_27dd69c0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredCosts_27dd69c0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_6e1ed1d0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_6e1ed1d0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_761ef1a8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtCurrent_761ef1a8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_05630b34-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccountsPayableCurrent_05630b34-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_40740782-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_40740782-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_0607a31a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_0607a31a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredGainOnSaleOfProperty" xlink:label="loc_us-gaap_DeferredGainOnSaleOfProperty_2a3b7496-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredGainOnSaleOfProperty_2a3b7496-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent_05fb619a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccruedIncomeTaxesCurrent_05fb619a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent_2a991f10-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_6e17fb62-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredRevenueCurrent_2a991f10-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_761f7682-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_761f7682-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_DeferredGainOnSaleOfBuildingNoncurrent" xlink:label="loc_csgp_DeferredGainOnSaleOfBuildingNoncurrent_269cdb03-84ac-7b7c-aa67-2b54679b32e1" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_DeferredGainOnSaleOfBuildingNoncurrent_269cdb03-84ac-7b7c-aa67-2b54679b32e1" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRentCreditNoncurrent" xlink:label="loc_us-gaap_DeferredRentCreditNoncurrent_2a6c0c50-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredRentCreditNoncurrent_2a6c0c50-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_2b46081a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_2b46081a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedIncomeTaxesNoncurrent" xlink:label="loc_us-gaap_AccruedIncomeTaxesNoncurrent_0609c91a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccruedIncomeTaxesNoncurrent_0609c91a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_85390368-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_85390368-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_6e1ed1d0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaap_PreferredStockValue_8fab7cfe-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PreferredStockValue_8fab7cfe-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_1e2a510e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CommonStockValue_1e2a510e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_06e972fe-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AdditionalPaidInCapital_06e972fe-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_062fd1c8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_062fd1c8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_a33a731a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_adc32df4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_a33a731a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_1e12e4ba-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_6e1ed1d0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CommitmentsAndContingencies_1e12e4ba-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_181e990a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_181e990a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_92dcda4e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_92dcda4e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_a118d45a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_a118d45a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_8b69df8c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_8b69df8c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_92652922-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_92652922-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_43eda0b2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_43eda0b2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_894a3350-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_894a3350-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_92ead8b0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_92ead8b0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_ProceedsFromExerciseOfStockOptionsAndEspp" xlink:label="loc_csgp_ProceedsFromExerciseOfStockOptionsAndEspp_6d51154a-4603-4381-4efb-2b547509a1d5" xlink:type="locator" />
    <calculationArc order="8" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_7ca2b500-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_ProceedsFromExerciseOfStockOptionsAndEspp_6d51154a-4603-4381-4efb-2b547509a1d5" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_3fcc8200-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_181e990a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_3fcc8200-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_181e990a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_93386666-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_93386666-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SaleLeasebackTransactionNetProceeds" xlink:label="loc_us-gaap_SaleLeasebackTransactionNetProceeds_a71a44ec-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_SaleLeasebackTransactionNetProceeds_a71a44ec-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_8abc6b7c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_8abc6b7c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_8acc97f4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7c8e1730-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_8acc97f4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_181e990a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_3283801c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_Depreciation_3283801c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdjustmentForAmortization" xlink:label="loc_us-gaap_AdjustmentForAmortization_072ed9b6-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AdjustmentForAmortization_072ed9b6-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_0c2f0a44-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_0c2f0a44-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown_3b858f16-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown_3b858f16-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_43ed111a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_43ed111a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_ab78f61e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ShareBasedCompensation_ab78f61e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_BusinessAcquisitionDeferredConsiderationLiabilityReversal" xlink:label="loc_csgp_BusinessAcquisitionDeferredConsiderationLiabilityReversal_5bde98f6-0850-45f4-99a8-2b6d6906843c" xlink:type="locator" />
    <calculationArc order="8" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_BusinessAcquisitionDeferredConsiderationLiabilityReversal_5bde98f6-0850-45f4-99a8-2b6d6906843c" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_2a198e26-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="9" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_2a198e26-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_94b5f6e8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="10" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_94b5f6e8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_62c142a0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="11" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_62c142a0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_630012d2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="12" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInIncomeTaxesPayableNetOfIncomeTaxesReceivable_630012d2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_63b112d0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="13" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_63b112d0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInDeposits" xlink:label="loc_us-gaap_IncreaseDecreaseInDeposits_62c52136-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="14" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInDeposits_62c52136-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_63119b74-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="15" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_63119b74-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_63454b68-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="16" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7cb5e5da-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredRevenue_63454b68-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_20119e50-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_20119e50-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_81a3933a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_20119e50-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_81a3933a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_82973dc8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_81a3933a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_82973dc8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_84b6d7b2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_81a3933a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_84b6d7b2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedStatementsOfOperations" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6058d0a0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6058d0a0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_8028df7e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6058d0a0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_OperatingIncomeLoss_8028df7e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_6a12f3d2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6058d0a0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_InvestmentIncomeInterest_6a12f3d2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_678fa826-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6058d0a0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_InterestExpense_678fa826-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_800dbf32-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_aacb810a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_800dbf32-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_SellingAndMarketingExpense_aacb810a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost_a17e942a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_800dbf32-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost_a17e942a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_5b9b5a38-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_800dbf32-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_5b9b5a38-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_0c1661b0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_800dbf32-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_0c1661b0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_5c8cb1f8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_a489395e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_5c8cb1f8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_Revenues_a489395e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_235acf32-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_5c8cb1f8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CostOfRevenue_235acf32-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/DocumentAndEntityInformationDocumentAndEntityInformation" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/EmployeeBenefitPlans" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/EmployeeBenefitPlansDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/EmployeeBenefitPlansTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/FairValue" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/FairValueDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/FairValueTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/Goodwill" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/GoodwillDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/GoodwillTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/IncomeTaxes" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/IncomeTaxesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsNet" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_2afbcf16-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_2a5d1178-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_2afbcf16-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_2a5d1178-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsGross" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_2a5d1178-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_2b20a430-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_2b20a430-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_2b0dbb4a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_2b0dbb4a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_2ad7a794-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_2ad7a794-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_2b23d3c6-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_2b23d3c6-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_2b6a68f4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_2b6a68f4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross" xlink:label="loc_us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross_29be095c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsUnrealizedLossesOnAvailableforSaleSecuritiesGross_29be095c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent_2b14df4c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsDeferredRent_2b14df4c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredIncome" xlink:label="loc_us-gaap_DeferredTaxAssetsDeferredIncome_2aa0b4b4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="8" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsDeferredIncome_2aa0b4b4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction" xlink:label="loc_us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction_2a79dfce-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="9" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_2acbdd92-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsDeferredGainOnSaleLeasebackTransaction_2a79dfce-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilities" xlink:label="loc_us-gaap_DeferredTaxLiabilities_2b61113c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_2a5d1178-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxLiabilities_2b61113c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPrepaidExpenses" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_27e0532e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_2b61113c-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_27e0532e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_2b4fcb20-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_2b61113c-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_2b4fcb20-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_2b6027fe-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_2b61113c-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_2b6027fe-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_2b3a4dc2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_2afbcf16-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_2b3a4dc2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_24375614-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit_24369b34-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_24375614-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CurrentFederalTaxExpenseBenefit_24369b34-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_24341a58-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_24375614-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_24341a58-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_2435b37c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_24375614-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CurrentForeignTaxExpenseBenefit_2435b37c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_TotalDeferredIncomeTaxPerYear" xlink:label="loc_csgp_TotalDeferredIncomeTaxPerYear_ac067122-0e9d-4b04-2f57-2b6d691681a8" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_29f1fa28-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_TotalDeferredIncomeTaxPerYear_ac067122-0e9d-4b04-2f57-2b6d691681a8" xlink:to="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_29f1fa28-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_2a56c570-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_TotalDeferredIncomeTaxPerYear_ac067122-0e9d-4b04-2f57-2b6d691681a8" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_2a56c570-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_2a123b3a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_TotalDeferredIncomeTaxPerYear_ac067122-0e9d-4b04-2f57-2b6d691681a8" xlink:to="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_2a123b3a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_617fd2d0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_617fd2d0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_61873264-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_61873264-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:label="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_6297a760-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_6297a760-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_615b3056-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_615b3056-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_6111b8ae-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_6111b8ae-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpense_6177185c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpense_6177185c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_614bcab2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_614bcab2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_61923b3c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="8" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_61923b3c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/IncomeTaxesTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/IntangiblesAndOtherAssets" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/IntangiblesAndOtherAssetsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_54e9c33c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_54b51c2c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_54e9c33c-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_54b51c2c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_54e3539e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_54e9c33c-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_54e3539e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/IntangiblesAndOtherAssetsTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/Investments" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/InvestmentsAvailableForSaleSecuritiesDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesAmortizedCost" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_0e08560e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAmortizedCost_0e08560e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_GrossUnrealizedGainsforAvailableForSaleSecurities" xlink:label="loc_csgp_GrossUnrealizedGainsforAvailableForSaleSecurities_e3b85646-f88f-11e2-a68d-22000a9d039f" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_GrossUnrealizedGainsforAvailableForSaleSecurities_e3b85646-f88f-11e2-a68d-22000a9d039f" xlink:type="arc" />
    <loc xlink:href="csgp-20131231.xsd#csgp_GrossUnrealizedLossesforAvailableForSaleSecurities" xlink:label="loc_csgp_GrossUnrealizedLossesforAvailableForSaleSecurities_20a17ede-f890-11e2-a68d-22000a9d039f" xlink:type="locator" />
    <calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_GrossUnrealizedLossesforAvailableForSaleSecurities_20a17ede-f890-11e2-a68d-22000a9d039f" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/InvestmentsDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_0dc7ccec-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue_0dc7ccec-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_0e0a0a6c-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue_0e0a0a6c-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_0dca1f24-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue_0dca1f24-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_0e0552d8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0dd57554-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue_0e0552d8-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/InvestmentsTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/LongTermDebt" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/LongTermDebtDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/LongTermDebtScheduleOfMaturitiesOfLongTermDebtDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_754fc3b0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7621d26a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_754fc3b0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7621d26a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_760cfcdc-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_754fc3b0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_760cfcdc-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_761ba6b0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_754fc3b0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_761ba6b0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_7616a25a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_754fc3b0-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_7616a25a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/LongTermDebtTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/NetIncomePerShare" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/NetIncomePerShareDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b93d27d4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_b91dcd62-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b93d27d4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_b91dcd62-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_6554f444-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_b93d27d4-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_6554f444-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/NetIncomePerShareTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/Organization" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/OrganizationDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/PropertyAndEquipment" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/PropertyAndEquipmentDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_940b342e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_9406abd4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_940b342e-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_9406abd4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_061c48ec-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_940b342e-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_061c48ec-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccounts" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccountsDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/ScheduleIiValuationAndQualifyingAccountsTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SegmentReporting" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SegmentReportingDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="csgp-20131231.xsd#csgp_TotalSegmentLiabilities" xlink:label="loc_csgp_TotalSegmentLiabilities_b3f5155d-4d09-df07-3f22-2b546a999f8b" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_TotalSegmentLiabilities_b3f5155d-4d09-df07-3f22-2b546a999f8b" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent" xlink:label="loc_us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent_05526e00-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_6e59ec02-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent_05526e00-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_602ea2e4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_602ea2e4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostOfGoodsSoldAmortization" xlink:label="loc_us-gaap_CostOfGoodsSoldAmortization_23078890-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_CostOfGoodsSoldAmortization_23078890-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_0c1661b0-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_0c1661b0-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_328d60be-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="4" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_328d60be-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_6a12f3d2-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_InvestmentIncomeInterest_6a12f3d2-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_678fa826-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="6" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_InterestExpense_678fa826-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="7" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_7cc2c354-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_610ca94a-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="csgp-20131231.xsd#csgp_SegmentReportingSegmentGrossAssets" xlink:label="loc_csgp_SegmentReportingSegmentGrossAssets_8566fa2d-8b88-86d2-6b13-2b5467ca43ee" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_csgp_SegmentReportingSegmentGrossAssets_8566fa2d-8b88-86d2-6b13-2b5467ca43ee" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_6ae6abb4-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_6ae6abb4-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableRelatedParties" xlink:label="loc_us-gaap_AccountsReceivableRelatedParties_05223d3e-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_0ce13e30-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccountsReceivableRelatedParties_05223d3e-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/SegmentReportingTables" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/StockholdersEquity" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/StockholdersEquityDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesAccumulatedOtherComprehensiveIncomeLossNetOfTaxDetails" xlink:type="extended">
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_062fd1c8-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_063c3aee-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_062fd1c8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_063c3aee-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_062d1690-9656-11e2-88e7-12313d1a0274" xlink:type="locator" />
    <calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_062fd1c8-9656-11e2-88e7-12313d1a0274" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_062d1690-9656-11e2-88e7-12313d1a0274" xlink:type="arc" />
  </calculationLink>
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesStockBasedCompensationExpenseDetails" xlink:type="extended" />
  <calculationLink xlink:role="http://www.costar.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
</linkbase>
