EXHIBIT A Restrictive Covenant

March 15, 2012

Dear Dermot:

This letter agreement outlines our understandings concerning your position as the Corporate Vice President of Human Resources of Automatic Data Processing, Inc. (“ADP”).

ADP and you agree as follows:

2.    Compensation and Benefits.

with ADP prior to June 30, 2012. Your actual FY’12 bonus shall be based upon your performance against the performance objectives set by the CEO in advance of your start date, subject to the following sentence. Your actual FY’12 and FY’13 bonus shall be no less than your target bonus for such periods, provided your employment does not terminate for any reason described in paragraphs 6.a through 6.d of this letter agreement.

(ii) The above and any subsequent grants of restricted stock that may be made to you from time-to-time shall be subject to the terms and conditions governing issuances of restricted stock under ADP’s 2008 Omnibus Award Plan.

4.Stock Options.

You shall be offered an initial stock option grant of 30,000 shares at the next meeting of the Compensation Committee following your start date. The next such meeting of the Compensation Committee is scheduled for June 2012. If the grant, along with the restrictive covenants associated with such grant, are accepted, such options will vest ratably in 25% increments on each of the first four anniversaries of the grant date, and otherwise in accordance with the terms of the grant.

5.     Minimum Stock Ownership Guidelines.

If your employment with ADP is terminated, you will receive the following compensation:

such disability and otherwise unable substantially to perform your services hereunder such that ADP recognizes you as qualified for ADP's long term disability ADP may terminate your employment, and ADP’s obligation to make payments to you (beyond previously accrued and unpaid amounts) shall cease on the date of such termination, other than the Accrued Obligations.

In the event your employment is terminated without Cause or if you resign for Good Reason, in either case, effective prior to May 1, 2015, then any stock and stock options originally granted under paragraphs 3(a)(i), 3(b) and 4 of this Agreement shall accelerate and vest in full, provided that any vested options must be exercised within 60 days of the date of acceleration. No payment herein shall be subject to mitigation.

your reporting line such that you report to someone other than the CEO, (3) a change in your duties and authority such that you no longer preside as the seniormost executive with overall responsibility for Human Resources, (4) a reduction in your Grade Level, or (5) a material breach by ADP of this Agreement or any other agreement to which you are a party; provided, however, you must communicate the existence of the Good Reason condition to ADP in writing no later than 60 days after you have actual knowledge of the existence of the Good Reason condition, and if the Company does not cure the condition within 30 days after receiving such notice, then your resignation for Good Reason shall be effective upon your written resignation tendered within the next 30 days.

(A) or (C) (relating to certain reimbursements and in-kind benefits) shall be paid or provided to you only to the extent that the expenses are not incurred, or the benefits are not provided, beyond the last day of the second calendar year following the calendar year in which your “separation from service” occurs; and provided further that such expenses are reimbursed no later than the last day of the third calendar year following the calendar year in which your “separation from service” occurs. To the extent any indemnification payment, expense reimbursement, or the provision of any in-kind benefit is determined to be subject to Section 409A (and not exempt pursuant to the prior sentence or otherwise), the amount of any such indemnification payment or expenses eligible for reimbursement, or the provision of any in-kind benefit, in one calendar year shall not affect the indemnification payment or provision of in-kind benefits or expenses eligible for reimbursement in any other calendar year (except for any life-time or other aggregate limitation applicable to medical expenses), and any indemnification payment or expenses will be reimbursed before the last day of the calendar year following the calendar year in which you incurred such indemnification payment or expenses, and in no event shall any right to indemnification payment or reimbursement or the provision of any in-kind benefit be subject to liquidation or exchange for another benefit.

If the foregoing correctly sets forth our understandings, please sign this letter agreement where indicated, whereupon it will become a binding agreement between us.

Automatic Data Processing, Inc.

By:/s/Carlos Rodriguez_______

Carlos Rodriguez

President and Chief Executive Officer

Accepted and Agreed:

Dermot O’Brien

Dated:__3-21-12________

I acknowledge that in my position(s) with Automatic Data Processing, Inc., its subsidiaries and affiliates (collectively “ADP”), I have access to confidential information and trade secrets of ADP and I enjoy substantial compensation and benefits from ADP. In consideration of such benefits and because it is in ADP’s best interests that all employees in executive positions execute restrictive covenants, I agree as follows:

1.     During the period that I am an ADP employee and ending twenty-four months after the date I cease to be an ADP employee for any reason whatsoever (the “Non-Competition Period”), I will not, directly or indirectly, become or be interested in, employed by, or associated with in any capacity, any person, corporation, partnership or other entity whatsoever (a “Person”) engaged in any aspect of ADP’s businesses, or businesses ADP has formal plans to enter on the date I cease to be an ADP employee (the “Termination Date”), in a capacity which is (i) either the same or similar to any capacity in which I was involved during the last two years of my employment by ADP or (ii) otherwise a senior or executive position. After the Termination Date, however, nothing shall prevent me from owning, as an inactive investor, securities of any competitor of ADP which is listed on a national securities exchange. Furthermore, after the Termination Date, I may become employed in a separate, autonomous division of a corporation or other entity, provided such division is not a competitor of ADP.

2.    During and after my employment by ADP, I will not use, or disclose to any Person any confidential information, trade secrets or proprietary information of ADP, its vendors, licensors, marketing partners or clients, learned by me during my employment and/or any of the names and addresses of clients of ADP. I acknowledge that I am prohibited from taking any confidential, proprietary or other materials or property of ADP with me upon termination of my employment. Upon termination of my employment, I shall return all ADP materials (including, without limitation, all memoranda and notes containing the names, addresses and/or needs of ADP clients and bona fide prospective clients) in my possession or over which I exercise control, regardless of whether such materials were prepared by ADP, me or a third party.

3.    During the Non-Competition Period, I shall not, on my behalf or on behalf of any other Person, directly or indirectly, solicit, contact, call upon, communicate with or attempt to communicate with any Person which was a client or a bona fide prospective client of ADP before the Termination Date to sell, market, license, lease or provide any software, product or service competitive or potentially competitive with any software, product or services sold, marketed, licensed, leased, provided or under development by ADP during the two-year period prior to the Termination Date.

4.     During the Non-Competition Period, I will not, directly or indirectly (i) hire, contract with, solicit, or encourage to leave ADP’s employ any ADP employee, or (ii) hire or contract with any former ADP employee within one year after the date such person ceases to be an ADP employee.

5.     During my employment by ADP, I shall not accept any position (unless such position is to commence after my employment ceases), compensation, reimbursement or funds, or their equivalent, from any Person engaged in any business in which ADP is engaged.

6.    A violation of the foregoing covenants not to compete, not to disclose, not to solicit and not to hire will cause irreparable injury to ADP. ADP shall be entitled, in addition to any other rights and

remedies it may have at law or in equity, to an injunction enjoining and restraining me from performing, and continuing in the performance of, any such violation.

7.     I understand and acknowledge that ADP shall have the sole and exclusive rights to anything relating to its actual or prospective business which I conceive or work on, either in whole or in part, while employed by ADP and that all such work product may be property of ADP as “works for hire” under federal copyright law and may also constitute ADP confidential and proprietary information. Accordingly, I:

(a) will promptly and fully disclose all such items to ADP and will not disclose such items to any other Person without ADP’s prior consent;

(b) will maintain on ADP’s behalf and surrender to ADP upon termination of my employment appropriate written records regarding all such items;

(c) will, but without personal expense, fully cooperate with ADP, execute all papers and perform all acts requested by ADP to establish, confirm or protect its exclusive rights in such items or to enable it to transfer legal title to such items, together with any patents that may be issued;

(d) will, but without personal expense, provide such information and true testimony as ADP may request regarding such items including, without limitation, items which I neither conceived nor worked on but regarding which I have knowledge because of my employment with ADP; and

(e) hereby assign to ADP, it successors and assigns, exclusive right, title and interest in and to all such items, including any patents which have been or may be issued.

8.    My obligations under this Agreement shall be binding upon me regardless of which office(s) of ADP I am employed at or position(s) I hold and shall inure to the benefit of any successors or assigns of ADP. This Agreement supplements and does not supersede any prior agreement(s) on the subject matter addressed herein.

9.    If any provision of this Agreement is invalid or unenforceable, the balance of this Agreement shall remain in effect. This Agreement shall be governed by, and construed in accordance with, the laws of the State of New Jersey. Any waiver of any provision of this Agreement shall be valid only if set forth in an instrument in writing signed by ADP. Any waiver of any provision shall not be construed as a subsequent waiver of the same provision, or a waiver of any other provision, of this Agreement. I acknowledge that the terms of this Agreement are reasonable and that I have had a reasonable opportunity to consult with an attorney before agreeing to the terms of this Agreement.

/s/Dermot O’Brien            
Dermot O’Brien

3-21-12                
Date