<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-12-31</periodOfReport>

    <issuer>
        <issuerCik>0001618921</issuerCik>
        <issuerName>Walgreens Boots Alliance, Inc.</issuerName>
        <issuerTradingSymbol>WBA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001587694</rptOwnerCik>
            <rptOwnerName>Gourlay Alexander W.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WALGREENS BOOTS ALLIANCE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>108 WILMOT ROAD</rptOwnerStreet2>
            <rptOwnerCity>DEERFIELD</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60015</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP and President of Walgreens</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>427650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>722907</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person acquired the common stock in exchange for his interest in the Alliance Boots Management Equity Plan in connection with the closing of the transaction described in this footnote.  On December 31, 2014, Walgreens Boots Alliance, Inc. (successor of Walgreen Co.) completed the acquisition of the 55% of the issued and outstanding share capital of Alliance Boots GmbH  it did not already own in exchange for GBP 3.133 billion, payable in cash in British pounds sterling, and 144,333,468 shares of Walgreens Boots Alliance, Inc. common stock, subject to certain specified adjustments.  On December 31, 2014, the closing price of Walgreens Boots Alliance, Inc. common stock was $76.20 per share.</footnote>
    </footnotes>

    <remarks>On December 31, 2014, Walgreens Boots Alliance, Inc., a Delaware corporation, became the successor of Walgreen Co., an Illinois corporation, pursuant to a merger to effect a reorganization of Walgreen Co. into a holding company structure. The merger resulted in Walgreens Boots Alliance, Inc.  becoming the parent holding company of Walgreen Co. and changed the company's domicile, but did not alter the proportionate interests of security holders.</remarks>

    <ownerSignature>
        <signatureName>/s/ Mark L. Dosier, Attorney-in-Fact</signatureName>
        <signatureDate>2015-01-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-12-31
0001618921
Walgreens Boots Alliance, Inc.
WBA
0001587694
Gourlay Alexander W.
WALGREENS BOOTS ALLIANCE, INC.
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
EVP and President of Walgreens
Common Stock
2014-12-31
4
A
0
427650
A
722907
D
The reporting person acquired the common stock in exchange for his interest in the Alliance Boots Management Equity Plan in connection with the closing of the transaction described in this footnote.  On December 31, 2014, Walgreens Boots Alliance, Inc. (successor of Walgreen Co.) completed the acquisition of the 55% of the issued and outstanding share capital of Alliance Boots GmbH  it did not already own in exchange for GBP 3.133 billion, payable in cash in British pounds sterling, and 144,333,468 shares of Walgreens Boots Alliance, Inc. common stock, subject to certain specified adjustments.  On December 31, 2014, the closing price of Walgreens Boots Alliance, Inc. common stock was $76.20 per share.
On December 31, 2014, Walgreens Boots Alliance, Inc., a Delaware corporation, became the successor of Walgreen Co., an Illinois corporation, pursuant to a merger to effect a reorganization of Walgreen Co. into a holding company structure. The merger resulted in Walgreens Boots Alliance, Inc.  becoming the parent holding company of Walgreen Co. and changed the company's domicile, but did not alter the proportionate interests of security holders.
/s/ Mark L. Dosier, Attorney-in-Fact
2015-01-02