<?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>0001342075</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>McCurdy Kay W</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Former BOD</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Fidelity Brokerage Services LLC</name>
        <address>
          <com:street1>900 Salem Street</com:street1>
          <com:city>Smithfield</com:city>
          <com:stateOrCountry>RI</com:stateOrCountry>
          <com:zipCode>02917</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>900</noOfUnitsSold>
      <aggregateMarketValue>197073.00</aggregateMarketValue>
      <noOfUnitsOutstanding>214246000</noOfUnitsOutstanding>
      <approxSaleDate>06/30/2023</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>05/11/2022</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>900</amountOfSecuritiesAcquired>
      <paymentDate>05/11/2022</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Kay W Mccurdy Rev Trust</name>
        <address>
          <com:street1>2850 Golf Road</com:street1>
          <com:city>Rolling Meadows</com:city>
          <com:stateOrCountry>IL</com:stateOrCountry>
          <com:zipCode>60008</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>05/03/2023</saleDate>
      <amountOfSecuritiesSold>1500</amountOfSecuritiesSold>
      <grossProceeds>317673.12</grossProceeds>
    </securitiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Kay W Mccurdy Rev Trust</name>
        <address>
          <com:street1>2850 Golf Road</com:street1>
          <com:city>Rolling Meadows</com:city>
          <com:stateOrCountry>IL</com:stateOrCountry>
          <com:zipCode>60008</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>05/09/2023</saleDate>
      <amountOfSecuritiesSold>1500</amountOfSecuritiesSold>
      <grossProceeds>324230.70</grossProceeds>
    </securitiesSoldInPast3Months>
    <remarks>This trade occurred in the Kay W Mccurdy Rev Trust account of which Kay McCurdy is a trustee.</remarks>
    <noticeSignature>
      <noticeDate>06/30/2023</noticeDate>
      <signature>/s/ Ryan Riviere, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Kay W Mccurdy</signature>
    </noticeSignature>
  </formData>
</edgarSubmission>
[{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4152}]
144
0001342075
XXXXXXXX
LIVE
0000354190
Arthur J. Gallagher & Co.
001-09761
2850 GOLF ROAD
ROLLING MEADOWS
IL
60008-4050
630-773-3800
McCurdy Kay W
Former BOD
Common
Fidelity Brokerage Services LLC
900 Salem Street
Smithfield
RI
02917
900
197073.00
214246000
06/30/2023
NYSE
Common
05/11/2022
Restricted Stock Vesting
Issuer
N
900
05/11/2022
Compensation
N
Kay W Mccurdy Rev Trust
2850 Golf Road
Rolling Meadows
IL
60008
Common
05/03/2023
1500
317673.12
Kay W Mccurdy Rev Trust
2850 Golf Road
Rolling Meadows
IL
60008
Common
05/09/2023
1500
324230.70
This trade occurred in the Kay W Mccurdy Rev Trust account of which Kay McCurdy is a trustee.
06/30/2023
/s/ Ryan Riviere, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Kay W Mccurdy