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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-07-16</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001020079</rptOwnerCik>
            <rptOwnerName>FOOTE WILLIAM C</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>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-07-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>94.95</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>34323</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Transaction effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person.</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/ Kelsey Chin, attorney-in-fact</signatureName>
        <signatureDate>2015-07-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2015-07-16
0001618921
Walgreens Boots Alliance, Inc.
WBA
0001020079
FOOTE WILLIAM C
WALGREENS BOOTS ALLIANCE, INC.
108 WILMOT ROAD
DEERFIELD
IL
60015
1
0
0
0
Common Stock
2015-07-16
4
S
0
3500
94.95
D
34323
D
Transaction effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person.
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/ Kelsey Chin, attorney-in-fact
2015-07-17