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  <xs:element id="csgp_SupplementalBalanceSheetInformationRelatedtoLeasesTableTextBlock" abstract="false" name="SupplementalBalanceSheetInformationRelatedtoLeasesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="csgp_ScheduleofSupplementalCashFlowInformationforLeasesTableTextBlock" abstract="false" name="ScheduleofSupplementalCashFlowInformationforLeasesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="csgp_ScheduleOfInterestExpenseTableTextBlock" abstract="false" name="ScheduleOfInterestExpenseTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="csgp_SubscriptionBasedLicensingAgreementMinimumTermYears" abstract="false" name="SubscriptionBasedLicensingAgreementMinimumTermYears" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="csgp_ResidentialMember" abstract="true" name="ResidentialMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_SubscriptionBasedContractsMember" abstract="true" name="SubscriptionBasedContractsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_PerformanceBasedRestrictedStockMember" abstract="true" name="PerformanceBasedRestrictedStockMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_DomainMember" abstract="true" name="DomainMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_NumberOfPortfolioSegments" abstract="false" name="NumberOfPortfolioSegments" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_NumberOfClassesOfTradeReceivablesBasedOnLocation" abstract="false" name="NumberOfClassesOfTradeReceivablesBasedOnLocation" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_NumberOfTradeReceivablesInInformationServicesPortfolio" abstract="false" name="NumberOfTradeReceivablesInInformationServicesPortfolio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_NumberOfTradeReceivablesInMultifamilyPortfolio" abstract="false" name="NumberOfTradeReceivablesInMultifamilyPortfolio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_NumberOfTradeReceivablesInLoopNetPortfolio" abstract="false" name="NumberOfTradeReceivablesInLoopNetPortfolio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_NumberOfTradeReceivablesInOtherMarketplacesPortfolioSegment" abstract="false" name="NumberOfTradeReceivablesInOtherMarketplacesPortfolioSegment" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_ArlingtonVAMember" abstract="true" name="ArlingtonVAMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_ArlingtonOfficeTowerMember" abstract="true" name="ArlingtonOfficeTowerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_BuildingTenantMember" abstract="true" name="BuildingTenantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_AssetAcquisitionOwnerOccupancyPercentage" abstract="false" name="AssetAcquisitionOwnerOccupancyPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="csgp_AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet" abstract="false" name="AssetAcquisitionAssetsAcquiredAndLiabilitiesAssumedNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LessorLeaseBuyoutPaymentReceivable" abstract="false" name="LessorLeaseBuyoutPaymentReceivable" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LessorNumberOfEqualBuyoutInstallments" abstract="false" name="LessorNumberOfEqualBuyoutInstallments" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="csgp_ExpensesAbstract" abstract="true" name="ExpensesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_DepreciationAndAmortizationLessorAssetUnderOperatingLease" abstract="false" name="DepreciationAndAmortizationLessorAssetUnderOperatingLease" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LessorOperatingLeaseIncomeExpenseNet" abstract="false" name="LessorOperatingLeaseIncomeExpenseNet" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_PercentageOfPropertyOccupied" abstract="false" name="PercentageOfPropertyOccupied" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="csgp_CoStarMember" abstract="true" name="CoStarMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_InformationservicesMember" abstract="true" name="InformationservicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_MultifamilyOnlineMarketplaceMember" abstract="true" name="MultifamilyOnlineMarketplaceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_LoopNetMember" abstract="true" name="LoopNetMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_NorthAmericaSegmentMember" abstract="true" name="NorthAmericaSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_InternationalSegmentMember" abstract="true" name="InternationalSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_ChangeinContractwithCustomerLiabilityRollForward" abstract="true" name="ChangeinContractwithCustomerLiabilityRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_ContractwithCustomerLiabilityPriorPeriodAmountsRecognized" abstract="false" name="ContractwithCustomerLiabilityPriorPeriodAmountsRecognized" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_ContractwithCustomerLiabilityNewDeferralsNetofAmountsRecognizedinCurrentPeriod" abstract="false" name="ContractwithCustomerLiabilityNewDeferralsNetofAmountsRecognizedinCurrentPeriod" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_ContractwithCustomerAssetEffectsofCurrencyTranslation" abstract="false" name="ContractwithCustomerAssetEffectsofCurrencyTranslation" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_CommissionsIncurred" abstract="false" name="CommissionsIncurred" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_CommissionsCapitalizedintheCurrentPeriod" abstract="false" name="CommissionsCapitalizedintheCurrentPeriod" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_CapitalizedContractCosts" abstract="false" name="CapitalizedContractCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_InformationServicesMember" abstract="true" name="InformationServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_OtherPortfolioSegmentMember" abstract="true" name="OtherPortfolioSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_MatterportMember" abstract="true" name="MatterportMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_VisualLeaseMember" abstract="true" name="VisualLeaseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_BusinessCombinationExchangeRatioOfCommonStock" abstract="false" name="BusinessCombinationExchangeRatioOfCommonStock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="csgp_BusinessAcquisitionReplacementEquityAwardsFairValue" abstract="false" name="BusinessAcquisitionReplacementEquityAwardsFairValue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAvailableForSaleDebtSecurities" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAvailableForSaleDebtSecurities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLitigationAccrual" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLitigationAccrual" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilities" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxAssetsNet" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxAssetsNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLitigationAccrual" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLitigationAccrual" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssetsAndLiabilitiesNet" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssetsAndLiabilitiesNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssets" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_OperatingLeaseCostAbstract" abstract="true" name="OperatingLeaseCostAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_FinanceLeaseCostAbstract" abstract="true" name="FinanceLeaseCostAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_FinanceLeaseExpense" abstract="false" name="FinanceLeaseExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract" abstract="true" name="CashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract" abstract="true" name="RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_GoodwillAcquiredDuringPeriodAndMeasurementPeriodAdjustment" abstract="false" name="GoodwillAcquiredDuringPeriodAndMeasurementPeriodAdjustment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_IndefiniteLivedIntangibleAssetsWrittenOff" abstract="false" name="IndefiniteLivedIntangibleAssetsWrittenOff" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_A2800SeniorNotesMember" abstract="true" name="A2800SeniorNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_CreditAgreement2024Member" abstract="true" name="CreditAgreement2024Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_A2020CreditAgreementMember" abstract="true" name="A2020CreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_RevolvingLoansAndLettersOfCreditMember" abstract="true" name="RevolvingLoansAndLettersOfCreditMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_AlternateBaseRateMember" abstract="true" name="AlternateBaseRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_DebtInstrumentParValueDiscountedRate" abstract="false" name="DebtInstrumentParValueDiscountedRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="csgp_LineOfCreditFacilityCovenantComplianceTotalLeverageRatio" abstract="false" name="LineOfCreditFacilityCovenantComplianceTotalLeverageRatio" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="csgp_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_FinanceLeaseLiabilityToBePaidDueAfterYearFour" abstract="false" name="FinanceLeaseLiabilityToBePaidDueAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityAfterYearFour" abstract="false" name="LongTermDebtMaturityAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsAbstract" abstract="true" name="LongTermDebtMaturityInterestPaymentsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsRemainderOfFiscalYear" abstract="false" name="LongTermDebtMaturityInterestPaymentsRemainderOfFiscalYear" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsYearOne" abstract="false" name="LongTermDebtMaturityInterestPaymentsYearOne" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsYearTwo" abstract="false" name="LongTermDebtMaturityInterestPaymentsYearTwo" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsYearThree" abstract="false" name="LongTermDebtMaturityInterestPaymentsYearThree" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsYearFour" abstract="false" name="LongTermDebtMaturityInterestPaymentsYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPaymentsAfterYearFour" abstract="false" name="LongTermDebtMaturityInterestPaymentsAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_LongTermDebtMaturityInterestPayments" abstract="false" name="LongTermDebtMaturityInterestPayments" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_NetIncomeLossBeforeInterestAndOtherIncomeExpenseIncomeTaxesDepreciationAndAmortizationEBITDA" abstract="false" name="NetIncomeLossBeforeInterestAndOtherIncomeExpenseIncomeTaxesDepreciationAndAmortizationEBITDA" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_AmortizationOfIntangibleAssetsCostofRevenue" abstract="false" name="AmortizationOfIntangibleAssetsCostofRevenue" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_AmortizationOfIntangibleAssetsNetOfAdjustments" abstract="false" name="AmortizationOfIntangibleAssetsNetOfAdjustments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_CostarGroupInc2007StockIncentivePlanMember" abstract="true" name="CostarGroupInc2007StockIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_CoStarGroupInc.2016StockIncentivePlanMember" abstract="true" name="CoStarGroupInc.2016StockIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_CoStarGroupInc.2021StockIncentivePlanMember" abstract="true" name="CoStarGroupInc.2021StockIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedInAcquisition" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedInAcquisition" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="csgp_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAssumedInAcquisitionWeightedAverageGrantDateFairValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAssumedInAcquisitionWeightedAverageGrantDateFairValue" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="csgp_PerformanceBasedRSAsWithMarketAndPerformanceConditionMember" abstract="true" name="PerformanceBasedRSAsWithMarketAndPerformanceConditionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_ShareBasedPaymentArrangementExpenseExpectedAnnualCompensation" abstract="false" name="ShareBasedPaymentArrangementExpenseExpectedAnnualCompensation" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="csgp_PerformanceBasedRSAsWithPerformanceConditionMember" abstract="true" name="PerformanceBasedRSAsWithPerformanceConditionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="csgp_PerformanceBasedRSAsWithoutMarketConditionMember" abstract="true" name="PerformanceBasedRSAsWithoutMarketConditionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
