<?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>0001596932</rptOwnerCik>
            <rptOwnerName>Berkowitz Jeffrey</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>Executive Vice President</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>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9566</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50594</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4986</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>76.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45608</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares issued upon satisfaction of the performance criteria applicable to this restricted stock unit award granted on September 15, 2014 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. 2013 Omnibus Incentive Plan, as amended (together with the related award agreement, as amended, the &quot;Plan&quot;).  In accordance with the Plan, the shares underlying these restricted stock units vested on December 31, 2014, the Second Step Closing Date (as defined in the Purchase and Option Agreement by and among Alliance Boots GmbH, AB Acquisitions Holdings Limited and Walgreen Co., dated as of June 18, 2012, as amended).</footnote>
        <footnote id="F2">Disposition relating to the satisfaction of tax withholding obligations upon the vesting of award granted in accordance with Rule 16b-3.</footnote>
        <footnote id="F3">Includes shares underlying restricted stock units issued in lieu of dividends (through December 12, 2014) on outstanding restricted 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>2015-01-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-12-31
0001618921
Walgreens Boots Alliance, Inc.
WBA
0001596932
Berkowitz Jeffrey
WALGREENS BOOTS ALLIANCE, INC.
108 WILMOT ROAD
DEERFIELD
IL
60015
0
1
0
0
Executive Vice President
Common Stock
2014-12-31
4
A
0
9566
0
A
50594
D
Common Stock
2014-12-31
4
F
0
4986
76.20
D
45608
D
Shares issued upon satisfaction of the performance criteria applicable to this restricted stock unit award granted on September 15, 2014 (not a derivative security within the meaning of Rule 16a-1(c) upon grant) under the Walgreen Co. 2013 Omnibus Incentive Plan, as amended (together with the related award agreement, as amended, the "Plan").  In accordance with the Plan, the shares underlying these restricted stock units vested on December 31, 2014, the Second Step Closing Date (as defined in the Purchase and Option Agreement by and among Alliance Boots GmbH, AB Acquisitions Holdings Limited and Walgreen Co., dated as of June 18, 2012, as amended).
Disposition relating to the satisfaction of tax withholding obligations upon the vesting of award granted in accordance with Rule 16b-3.
Includes shares underlying restricted stock units issued in lieu of dividends (through December 12, 2014) on outstanding restricted 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
2015-01-02