FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * MADISON DEARBORN PARTNERS LLC   2. Issuer Name and Ticker or Trading Symbol CDW Corp [CDW] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O MADISON DEARBORN PARTNERS, LLC, 70 W. MADISON STREET, SUITE 4600 3. Date of Earliest Transaction (Month/Day/Year) 12/18/2013 (Street) CHICAGO, IL 60602 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, par value $0.01 12/18/2013   S   1,163,334 (1) D $ 20.5 58,093,318 (2) I See footnotes (2) (3) (4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MADISON DEARBORN PARTNERS LLC C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
Madison Dearborn Capital Partners V - A L P C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
Madison Dearborn Capital Partners V - C L P C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
MADISON DEARBORN CAPITAL PARTNERS V EXECUTIVE-A L P C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
MDCP Co-Investors (CDW) LP C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
MADISON DEARBORN PARTNERS V-A&C, L.P. C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X
MENCOFF SAMUEL M C/O MADISON DEARBORN PARTNERS, LLC 70 W. MADISON STREET, SUITE 4600 CHICAGO, IL 60602		X

Signatures

Madison Dearborn Partners LLC by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
Madison Dearborn Capital Partners V-A, L.P. by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
Madison Dearborn Capital Partners V-C, L.P. by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
Madison Dearborn Capital Partners V Executive-A, L.P. by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
MDCP Co-Investors (CDW), L.P. by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
Madison Dearborn Partners V - A&C, L.P. by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date
Samuel M. Mencoff by /s/ James S. Rowe, under Power of Attorney		12/20/2013
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Consists of 759,387 shares sold by Madison Dearborn Capital Partners V-A, L.P. ("MDP A"), 201,452 shares sold by Madison Dearborn Capital Partners V-C, L.P. ("MDP C"), 7,630 shares sold by Madison Dearborn Capital Partners V Executive-A, L.P. ("MDP Exec") and 194,865 shares sold by MDCP Co-Investor (CDW), L.P. ("MDP Co-Investor"), all pursuant to the underwriters' exercise of their option to purchase additional shares in an underwritten secondary offering.
(2)	Consists of 37,921,416 shares held directly by MDP A, 10,059,896 shares held directly by MDP C, 381,035 shares held directly by MDP Exec and 9,730,971 shares held directly by MDCP Co-Investor. Madison Dearborn Partners V-A&C, L.P. ("MDP V") is the general partner of MDP A, MDP C, MDP Exec and MDP Co-Investor. Madison Dearborn Partners, LLC ("MDP") is the general partner of MDP V. As the sole members of a limited partner committee of MDP V that has the power, acting by majority vote, to vote or dispose of the shares directly held by MDP A, MDP C, MDP Exec and MDP Co-Investor, Paul J. Finnegan and Samuel M. Mencoff may be deemed to have shared voting and investment power over such shares. Each of Messrs. Finnegan and Mencoff and MDP V hereby disclaims any beneficial ownership of any shares held by MDP A, MDP C, MDP Exec and MDP Co-Investor except to the extent of its or his pecuniary interest therein.
(3)	Mr. Mencoff has an indirect pecuniary interest in the shares of CDW Corporation's common stock held of record by the various MDP funds described above through his investment in MDP V. Each of MDP A, MDP C, MDP Exec and MDP Co-Investor and Mr. Mencoff may be deemed to share beneficial ownership of the reported securities and expressly disclaims beneficial ownership of such shares except to the extent of its or his pecuniary interest therein.
(4)	Mr. Finnegan has separately filed a Form 4.

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