<?xml version="1.0" encoding="UTF-8"?><ns2:edgarSubmission xmlns:com="http://www.sec.gov/edgar/common" xmlns:ns2="http://www.sec.gov/edgar/ownership">
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                    <ns2:ccc>XXXXXXXX</ns2:ccc>
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            </ns2:filer>
            <ns2:liveTestFlag>LIVE</ns2:liveTestFlag>



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        <ns2:issuerInfo>
            <ns2:issuerCik>0001057352</ns2:issuerCik>
            <ns2:issuerName>CoStar Group, Inc.</ns2:issuerName>
            <ns2:secFileNumber>000-24531</ns2:secFileNumber>
            <ns2:issuerAddress>
                <com:street1>1331 L Street, Northwest</com:street1>
                <com:city>Washington</com:city>
                <com:stateOrCountry>DC</com:stateOrCountry>
                <com:zipCode>20005</com:zipCode>
            </ns2:issuerAddress>
            <ns2:issuerContactPhone>1-800-204-5960</ns2:issuerContactPhone>
            <ns2:nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Christopher J Nassetta</ns2:nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <ns2:relationshipsToIssuer>
                <ns2:relationshipToIssuer>Director</ns2:relationshipToIssuer>
            </ns2:relationshipsToIssuer>
        </ns2:issuerInfo>
        <ns2:securitiesInformation>
            <ns2:securitiesClassTitle>common stock</ns2:securitiesClassTitle>
            <ns2:brokerOrMarketmakerDetails>
                <ns2:name>Goldman Sachs &amp; Co. LLC</ns2:name>
                <ns2:address>
                    <com:street1>200 West Street</com:street1>
                    <com:city>New York</com:city>
                    <com:stateOrCountry>NY</com:stateOrCountry>
                    <com:zipCode>10282</com:zipCode>
                </ns2:address>
            </ns2:brokerOrMarketmakerDetails>
            <ns2:noOfUnitsSold>1500</ns2:noOfUnitsSold>
            <ns2:aggregateMarketValue>116798</ns2:aggregateMarketValue>
            <ns2:noOfUnitsOutstanding>408363368</ns2:noOfUnitsOutstanding>
            <ns2:approxSaleDate>11/08/2023</ns2:approxSaleDate>
            <ns2:securitiesExchangeName>NASD</ns2:securitiesExchangeName>
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        <ns2:securitiesToBeSold>
            <ns2:securitiesClassTitle>Common stock</ns2:securitiesClassTitle>
            <ns2:acquiredDate>09/20/2018</ns2:acquiredDate>
            <ns2:natureOfAcquisitionTransaction>Acquired as compensation -- restricted stock awards</ns2:natureOfAcquisitionTransaction>
            <ns2:nameOfPersonfromWhomAcquired>Issuer</ns2:nameOfPersonfromWhomAcquired>
            <ns2:isGiftTransaction>N</ns2:isGiftTransaction>
            <ns2:amountOfSecuritiesAcquired>920</ns2:amountOfSecuritiesAcquired>
            <ns2:paymentDate>10/01/2021</ns2:paymentDate>
            <ns2:natureOfPayment>Compensation</ns2:natureOfPayment>
        </ns2:securitiesToBeSold>
        <ns2:securitiesToBeSold>
            <ns2:securitiesClassTitle>Common stock</ns2:securitiesClassTitle>
            <ns2:acquiredDate>09/19/2019</ns2:acquiredDate>
            <ns2:natureOfAcquisitionTransaction>Acquired as compensation - restricted stock awards</ns2:natureOfAcquisitionTransaction>
            <ns2:nameOfPersonfromWhomAcquired>Issuer</ns2:nameOfPersonfromWhomAcquired>
            <ns2:isGiftTransaction>N</ns2:isGiftTransaction>
            <ns2:amountOfSecuritiesAcquired>580</ns2:amountOfSecuritiesAcquired>
            <ns2:paymentDate>10/01/2021</ns2:paymentDate>
            <ns2:natureOfPayment>Compensation</ns2:natureOfPayment>
        </ns2:securitiesToBeSold>
        <ns2:nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</ns2:nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <ns2:noticeSignature>
            <ns2:noticeDate>11/08/2023</ns2:noticeDate>
            <ns2:planAdoptionDates/>
            <ns2:signature>Goldman Sachs &amp; Co. LLC on behalf of Christopher J Nassetta</ns2:signature>
        </ns2:noticeSignature>
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144
1078095
XXXXXXXX
LIVE
0001057352
CoStar Group, Inc.
000-24531
1331 L Street, Northwest
Washington
DC
20005
1-800-204-5960
Christopher J Nassetta
Director
common stock
Goldman Sachs & Co. LLC
200 West Street
New York
NY
10282
1500
116798
408363368
11/08/2023
NASD
Common stock
09/20/2018
Acquired as compensation -- restricted stock awards
Issuer
N
920
10/01/2021
Compensation
Common stock
09/19/2019
Acquired as compensation - restricted stock awards
Issuer
N
580
10/01/2021
Compensation
Y
11/08/2023
Goldman Sachs & Co. LLC on behalf of Christopher J Nassetta