<SEC-DOCUMENT>0001127602-20-010830.txt : 20200316
<SEC-HEADER>0001127602-20-010830.hdr.sgml : 20200316
<ACCEPTANCE-DATETIME>20200316170642
ACCESSION NUMBER:		0001127602-20-010830
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20200312
FILED AS OF DATE:		20200316
DATE AS OF CHANGE:		20200316

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Miskel Christopher C.
		CENTRAL INDEX KEY:			0001804681

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09761
		FILM NUMBER:		20718059

	MAIL ADDRESS:	
		STREET 1:		2850 GOLF ROAD
		CITY:			ROLLING MEADOWS
		STATE:			IL
		ZIP:			60008

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Arthur J. Gallagher & Co.
		CENTRAL INDEX KEY:			0000354190
		STANDARD INDUSTRIAL CLASSIFICATION:	INSURANCE AGENTS BROKERS & SERVICES [6411]
		IRS NUMBER:				362151613
		STATE OF INCORPORATION:			IL
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2850 GOLF ROAD
		CITY:			ROLLING MEADOWS
		STATE:			IL
		ZIP:			60008-4050
		BUSINESS PHONE:		630-773-3800

	MAIL ADDRESS:	
		STREET 1:		2850 GOLF ROAD
		CITY:			ROLLING MEADOWS
		STATE:			IL
		ZIP:			60008-4050

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ARTHUR J. GALLAGHER & CO.
		DATE OF NAME CHANGE:	20190819

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GALLAGHER ARTHUR J & CO
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>form3.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2020-03-12</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000354190</issuerCik>
        <issuerName>Arthur J. Gallagher &amp; Co.</issuerName>
        <issuerTradingSymbol>AJG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001804681</rptOwnerCik>
            <rptOwnerName>Miskel Christopher C.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2850 GOLF ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROLLING MEADOWS</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60008</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>/s/ April Hanes-Dowd, by power of attorney</signatureName>
        <signatureDate>2020-03-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>doc1.txt
<DESCRIPTION>POWER OF ATTORNEY (PUBLIC):
<TEXT>

POWER OF ATTORNEY

       Know all by these presents, that the undersigned hereby constitutes and
appoints each of Walter D. Bay, Richard C. Cary, Seth Diehl and April
Hanes-Dowd his true and lawful attorney-in-fact to:

1. execute and file for and on behalf of the undersigned the Form ID
Uniform Application for Access Codes to File on EDGAR;
2. execute for and on behalf of the undersigned Forms?3, 4, and 5 in
accordance with Section?16(a) of the Securities Exchange Act of 1934
and the rules thereunder;
3. do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to complete and execute any such
Form?3, 4, or 5, complete and execute any amendment or amendments
thereto, and timely file such form with the United States Securities
and Exchange Commission and any other authority; and
4. take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of
benefit to, in the best interest of, or legally required by, the
undersigned, it being understood that the documents executed by
such attorney-in-fact on behalf of the undersigned pursuant to this Power
of Attorney shall be in such form and shall contain such terms and
conditions as such attorney-in-fact may approve in his or her discretion.
       The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the
rights and powers herein granted, as fully to all intents and purposes
as the undersigned might or could do if personally present, with full power
of substitution or revocation, hereby ratifying and confirming all that
such attorney-in-fact, or his or her substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and
the rights and powers herein granted. The undersigned acknowledges that
the foregoing attorneys-in-fact, in servingin such capacity at the request
of the undersigned, are not assuming any ofthe undersigned's responsibilities
to comply with Section?16 of the Securities Exchange Act of 1934.
       This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms?3, 4, and 5 with respect to
his holdings of and transactions in securities issued by
Arthur J. Gallagher & Co., unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.
IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 20th day of February, 2020.

___/s/ Chris Miskel______________
                 Signature

_Christopher C. Miskel___________
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
