UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ☐                             Filed by a Party other than the Registrant  ☒

Check the appropriate box:

☐	Preliminary Proxy Statement
☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting material Pursuant to §240.14a-12

Automatic Data Processing, Inc.

(Name of Registrant as Specified In Its Charter)

William A. Ackman

Veronica M. Hagen

V. Paul Unruh

Pershing Square Capital Management, L.P.

PS Management GP, LLC

Pershing Square, L.P.

Pershing Square II, L.P.

Pershing Square International, Ltd.

Pershing Square Holdings, Ltd.

Pershing Square VI Master, L.P.

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

☒	No fee required.
☐	Fee computed on table below per Exchange Act Rules 14a-6(i)(4) and 0-11.
	1)	Title of each class of securities to which transaction applies:
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	4)	Proposed maximum aggregate value of transaction:
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☐	Fee paid previously with preliminary materials.
☐	Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.
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On September 14, 2017, Pershing Square Capital Management, L.P. and certain affiliates sent the following e-mail to certain subscribers of www.ADPascending.com:

Subscribe Past Issues Translate RSS View this email in your browser September 14, 2017 Thank you for your interest in ADP Ascending. Below find a list of pages that have been updated with new or changed content. Shareholder Materials: Proxy Supplement LEGAL NOTICE, DISCLAIMER AND FORWARD-LOOKING INFORMATION Pershing Square Capital Management, L.P. (“Pershing Square”) and certain of its affiliated funds have filed with the Securities and Exchange Commission (the “SEC”) a definitive proxy statement and accompanying GOLD proxy card to be used to solicit proxies in connection with the upcoming annual meeting of stockholders (the “Annual Meeting”) of Automatic Data Processing, Inc. (the “Company”) and the election of a slate of director nominees at the Annual Meeting (the “Solicitation”). Stockholders are advised to read the proxy statement and any other documents related to the Solicitation because they contain important information, including information relating to the participants in the Solicitation. These materials and other materials Filed by Pershing Square with the SEC in connection with the Solicitation are available at no charge on the SEC’s website at http://www.sec.gov. The definitive proxy statement and other relevant documents filed by Pershing Square with the SEC are also available, without charge, by directing a request to Pershing Square’s proxy solicitor, D.F. King & Co., Inc., 48 Wall Street, 22nd Floor, New York, New York 10005 (Call Collect: (212) 269-5550; Call Toll Free: (866) 342-1635) or email:ADP@dfking.com. William A. Ackman, Veronica M. Hagen, V. Paul Unruh, Pershing Square, PS Management GP, LLC (“PS Management”), Pershing Square, L.P., Pershing Square II, L.P., Pershing Square International, Ltd., Pershing Square Holdings, Ltd. and Pershing Square VI Master, L.P. may be deemed “participants” under SEC rules in the Solicitation. William A. Ackman, Pershing Square and PS Management may be deemed to beneficially own the equity securities of the Company described in Pershing Square’s statement on Schedule 13D initially filed with the SEC on August 7, 2017 (the “Schedule 13D”), as it may be amended from time to time. Except as described in the Schedule 13D, none of the individuals listed above has a direct or indirect interest, by security holdings or otherwise, in the Company or the matters to be acted upon, if any, in connection with the Annual Meeting. Neither the press release or related email notification is an offer to purchase nor a solicitation of an offer to sell any securities of any investment funds managed by Pershing Square, or the Company, or of any other person. While certain funds managed by Pershing Square have invested in the common stock of and/or derivatives referencing, the Company, Pershing Square is not an affiliate of the Company and is not authorized to disseminate any information for or on behalf of the Company. Copyright @ 2017 ADP Ascending, All rights reserved. Want to change how you receive these emails? You can update your preferences or unsubscribe from this list.

CERTAIN INFORMATION CONCERNING THE PARTICIPANTS

Pershing Square Capital Management, L.P. (“Pershing Square”) and certain of its affiliated funds have filed with the Securities and Exchange Commission (the “SEC”) a definitive proxy statement and accompanying GOLD proxy card to be used to solicit proxies in connection with the upcoming annual meeting of stockholders (the “Annual Meeting”) of Automatic Data Processing, Inc. (the “Company”) and the election of a slate of director nominees at the Annual Meeting (the “Solicitation”). Stockholders are advised to read the proxy statement and any other documents related to the Solicitation because they contain important information, including information relating to the participants in the Solicitation. These materials and other materials filed by Pershing Square with the SEC in connection with the Solicitation are available at no charge on the SEC’s website at http://www.sec.gov. The definitive proxy statement and other relevant documents filed by Pershing Square with the SEC are also available, without charge, by directing a request to Pershing Square’s proxy solicitor, D.F. King & Co., Inc., 48 Wall Street, 22nd Floor, New York, New York 10005 (Call Collect: (212) 269-5550; Call Toll Free: (866) 342-1635) or email: ADP@dfking.com.

William A. Ackman, Veronica M. Hagen, V. Paul Unruh, Pershing Square, PS Management GP, LLC (“PS Management”), Pershing Square, L.P., Pershing Square II, L.P., Pershing Square International, Ltd., Pershing Square Holdings, Ltd. and Pershing Square VI Master, L.P. may be deemed “participants” under SEC rules in the Solicitation. William A. Ackman, Pershing Square and PS Management may be deemed to beneficially own the equity securities of the Company described in Pershing Square’s statement on Schedule 13D initially filed with the SEC on August 7, 2017 (the “Schedule 13D”), as it may be amended from time to time. Except as described in the Schedule 13D or the definitive proxy statement, none of the individuals listed above has a direct or indirect interest, by security holdings or otherwise, in the Company or the matters to be acted upon, if any, in connection with the Annual Meeting.