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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-01-15</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001376358</rptOwnerCik>
            <rptOwnerName>SCHLICHTING NANCY M</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>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-01-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>284.167</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>74.78</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>284.167</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49578.8</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The phantom stock is issued as non-employee director compensation under the Walgreens Boots Alliance, Inc. 2013 Omnibus Incentive Plan, as amended, and converts into the cash value of the company's common stock on a one-for-one basis.</footnote>
        <footnote id="F2">To be settled in two installments, the first of which occurs within thirty days following termination of service as a director, and the second, one year after the first settlement date.</footnote>
        <footnote id="F3">Includes phantom stock units issued in lieu of dividends (through December 12, 2014) on outstanding phantom stock units.</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>2015-01-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2015-01-15
0001618921
Walgreens Boots Alliance, Inc.
WBA
0001376358
SCHLICHTING NANCY M
WALGREENS BOOTS ALLIANCE, INC.
108 WILMOT ROAD
DEERFIELD
IL
60015
1
0
0
0
Phantom Stock Units
2015-01-15
4
A
0
284.167
74.78
A
Common Stock
284.167
49578.8
D
The phantom stock is issued as non-employee director compensation under the Walgreens Boots Alliance, Inc. 2013 Omnibus Incentive Plan, as amended, and converts into the cash value of the company's common stock on a one-for-one basis.
To be settled in two installments, the first of which occurs within thirty days following termination of service as a director, and the second, one year after the first settlement date.
Includes phantom stock units issued in lieu of dividends (through December 12, 2014) on outstanding phantom stock units.
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
2015-01-16