<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001784277</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <issuerInfo>
      <issuerCik>0000354190</issuerCik>
      <issuerName>Arthur J. Gallagher &amp; Co.</issuerName>
      <secFileNumber>001-09761</secFileNumber>
      <issuerAddress>
        <com:street1>2850 GOLF ROAD</com:street1>
        <com:city>ROLLING MEADOWS</com:city>
        <com:stateOrCountry>IL</com:stateOrCountry>
        <com:zipCode>60008-4050</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>630-773-3800</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Matrix Trust Co</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Trustee for Arthur J Gallagher Rabbi Trust</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Pershing LLC</name>
        <address>
          <com:street1>One Pershing Square</com:street1>
          <com:city>Jersey City</com:city>
          <com:stateOrCountry>NJ</com:stateOrCountry>
          <com:zipCode>07399</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>15000</noOfUnitsSold>
      <aggregateMarketValue>3238500.00</aggregateMarketValue>
      <noOfUnitsOutstanding>256900000</noOfUnitsOutstanding>
      <approxSaleDate>06/16/2026</approxSaleDate>
      <securitiesExchangeName>Nasdaq Stock Market</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <acquiredDate>01/01/2012</acquiredDate>
      <natureOfAcquisitionTransaction>Open Market Purchase</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Open Market</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>15000</amountOfSecuritiesAcquired>
      <paymentDate>01/01/2012</paymentDate>
      <natureOfPayment>Cash at time of purchase</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>03/18/2026</saleDate>
      <amountOfSecuritiesSold>139</amountOfSecuritiesSold>
      <grossProceeds>29055.01</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>03/24/2026</saleDate>
      <amountOfSecuritiesSold>238</amountOfSecuritiesSold>
      <grossProceeds>51721.56</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>03/26/2026</saleDate>
      <amountOfSecuritiesSold>2256</amountOfSecuritiesSold>
      <grossProceeds>475497.12</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/02/2026</saleDate>
      <amountOfSecuritiesSold>1468</amountOfSecuritiesSold>
      <grossProceeds>320175.35</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/06/2026</saleDate>
      <amountOfSecuritiesSold>900</amountOfSecuritiesSold>
      <grossProceeds>197842.65</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Pheonix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/15/2026</saleDate>
      <amountOfSecuritiesSold>11</amountOfSecuritiesSold>
      <grossProceeds>2466.11</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/21/2026</saleDate>
      <amountOfSecuritiesSold>198</amountOfSecuritiesSold>
      <grossProceeds>44305.04</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/24/2026</saleDate>
      <amountOfSecuritiesSold>57</amountOfSecuritiesSold>
      <grossProceeds>12295.64</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>04/29/2026</saleDate>
      <amountOfSecuritiesSold>95</amountOfSecuritiesSold>
      <grossProceeds>20031.99</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/06/2026</saleDate>
      <amountOfSecuritiesSold>639</amountOfSecuritiesSold>
      <grossProceeds>127063.61</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/08/2026</saleDate>
      <amountOfSecuritiesSold>418</amountOfSecuritiesSold>
      <grossProceeds>83335.56</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/11/2026</saleDate>
      <amountOfSecuritiesSold>28</amountOfSecuritiesSold>
      <grossProceeds>5554.17</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/13/2026</saleDate>
      <amountOfSecuritiesSold>84</amountOfSecuritiesSold>
      <grossProceeds>16137.53</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/20/2026</saleDate>
      <amountOfSecuritiesSold>1570</amountOfSecuritiesSold>
      <grossProceeds>318226.94</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>05/26/2026</saleDate>
      <amountOfSecuritiesSold>56</amountOfSecuritiesSold>
      <grossProceeds>11365.94</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/01/2026</saleDate>
      <amountOfSecuritiesSold>1932</amountOfSecuritiesSold>
      <grossProceeds>395557.06</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/03/2026</saleDate>
      <amountOfSecuritiesSold>284</amountOfSecuritiesSold>
      <grossProceeds>57582.79</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/05/2026</saleDate>
      <amountOfSecuritiesSold>2420</amountOfSecuritiesSold>
      <grossProceeds>522667.61</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/08/2026</saleDate>
      <amountOfSecuritiesSold>147</amountOfSecuritiesSold>
      <grossProceeds>31421.70</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/09/2026</saleDate>
      <amountOfSecuritiesSold>33</amountOfSecuritiesSold>
      <grossProceeds>7146.58</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/10/2026</saleDate>
      <amountOfSecuritiesSold>18</amountOfSecuritiesSold>
      <grossProceeds>3995.95</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Matrix Trust Company</name>
        <address>
          <com:street1>2800 North Central Ave</com:street1>
          <com:street2>Suite 900</com:street2>
          <com:city>Phoenix</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85004</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <saleDate>06/11/2026</saleDate>
      <amountOfSecuritiesSold>1153</amountOfSecuritiesSold>
      <grossProceeds>255900.42</grossProceeds>
    </securitiesSoldInPast3Months>
    <remarks>It is anticipated that sales covered by this form will be made within the period beginning 6/17/2025 and ending 9/14/2026</remarks>
    <noticeSignature>
      <noticeDate>06/16/2026</noticeDate>
      <signature>Eric Simpson</signature>
    </noticeSignature>
  </formData>
</edgarSubmission>
