content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
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  <submissionType>144</submissionType>
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  <filer>
  <filerCredentials>
  <cik>0001665262</cik>
  <ccc>XXXXXXXX</ccc>
  </filerCredentials>
  </filer>
  <liveTestFlag>LIVE</liveTestFlag>
  </filerInfo>
  </headerData>
  <formData>
  <issuerInfo>
  <issuerCik>0001842718</issuerCik>
  <issuerName>Integral Ad Science Holding Corp.</issuerName>
  <secFileNumber>001-40557</secFileNumber>
  <issuerAddress>
  <street1 xmlns="http://www.sec.gov/edgar/common">99 Wall Street</street1>
  <street2 xmlns="http://www.sec.gov/edgar/common">#1950</street2>
  <city xmlns="http://www.sec.gov/edgar/common">New York</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">NY</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">10005</zipCode>
  </issuerAddress>
  <issuerContactPhone>646-278-4871</issuerContactPhone>
  <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Vista Equity Partners Fund VI, L.P.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
  <relationshipsToIssuer>
  <relationshipToIssuer>Owner</relationshipToIssuer>
  </relationshipsToIssuer>
  </issuerInfo>
  <securitiesInformation>
  <securitiesClassTitle>Common</securitiesClassTitle>
  <brokerOrMarketmakerDetails>
  <name>Jefferies LLC</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">520 Madison Avenue</street1>
  <city xmlns="http://www.sec.gov/edgar/common">New York</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">NY</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">10022</zipCode>
  </address>
  </brokerOrMarketmakerDetails>
  <noOfUnitsSold>3229655</noOfUnitsSold>
  <aggregateMarketValue>61912486.35</aggregateMarketValue>
  <noOfUnitsOutstanding>154927770</noOfUnitsOutstanding>
  <approxSaleDate>06/15/2023</approxSaleDate>
  <securitiesExchangeName>Nasdaq</securitiesExchangeName>
  </securitiesInformation>
  <securitiesToBeSold>
  <securitiesClassTitle>Common Stock, par value $0.001 per share</securitiesClassTitle>
  <acquiredDate>06/29/2021</acquiredDate>
  <natureOfAcquisitionTransaction>Pre-IPO Reorganization</natureOfAcquisitionTransaction>
  <nameOfPersonfromWhomAcquired>Integral Ad Science Holding LLC</nameOfPersonfromWhomAcquired>
  <isGiftTransaction>N</isGiftTransaction>
  <amountOfSecuritiesAcquired>58393646</amountOfSecuritiesAcquired>
  <paymentDate>06/29/2021</paymentDate>
  <natureOfPayment>Securities of the issuer were received in connection with a series of reorganization transactions prior to the issuer's IPO.</natureOfPayment>
  </securitiesToBeSold>
  <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
  <remarks>Aggregate Market Value is based on the closing price on June 15, 2023. Number of Shares or Other Units Outstanding as of May 2, 2023 (as reported on the Issuer's Form 10-Q for the quarterly period ended March 31, 2023, filed with the Securities and Exchange Commission on May 4, 2023).</remarks>
  <noticeSignature>
  <noticeDate>06/15/2023</noticeDate>
  <signature>/s/ Robert F. Smith</signature>
  </noticeSignature>
  </formData>
  </edgarSubmission>
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text: 144
  0001665262
  XXXXXXXX
  LIVE
  0001842718
  Integral Ad Science Holding Corp.
  001-40557
  99 Wall Street
  #1950
  New York
  NY
  10005
  646-278-4871
  Vista Equity Partners Fund VI, L.P.
  Owner
  Common
  Jefferies LLC
  520 Madison Avenue
  New York
  NY
  10022
  3229655
  61912486.35
  154927770
  06/15/2023
  Nasdaq
  Common Stock, par value $0.001 per share
  06/29/2021
  Pre-IPO Reorganization
  Integral Ad Science Holding LLC
  N
  58393646
  06/29/2021
  Securities of the issuer were received in connection with a series of reorganization transactions prior to the issuer's IPO.
  Y
  Aggregate Market Value is based on the closing price on June 15, 2023. Number of Shares or Other Units Outstanding as of May 2, 2023 (as reported on the Issuer's Form 10-Q for the quarterly period ended March 31, 2023, filed with the Securities and Exchange Commission on May 4, 2023).
  06/15/2023
  /s/ Robert F. Smith