Ownership Submission
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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(Print or Type Responses)
1. Name and Address of Reporting Person *
MADISON DEARBORN PARTNERS III LP
   2. Issuer Name and Ticker or Trading Symbol
PACKAGING CORP OF AMERICA [PKG] 		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)
THREE FIRST NATIONAL PLAZA, SUITE 3800		 3. Date of Earliest Transaction (Month/Day/Year)
04/20/2007
(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, $0.01 par value 04/20/2007   J(1)   5,000,000 D $ 0 6,773,010 I By PCA Holdings, LLC (2) (3)

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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 III LP
THREE FIRST NATIONAL PLAZA
SUITE 3800
CHICAGO, IL 60602		     X    
MADISON DEARBORN CAPITAL PARTNERS III LP
THREE FIRST NATIONAL PLAZA
SUITE 3800
CHICAGO, IL 60602		     X    
PCA HOLDINGS LLC
THREE FIRST NATIONAL PLAZA
SUITE 3800
CHICAGO, IL 60602		     X    

Signatures

 /s/ Madison Dearborn Partners III, L.P., by Madison Dearborn Partners, LLC, its General Partner, by Mark B. Tresnowski, its Managing Director   04/20/2007
**Signature of Reporting Person Date
 /s/ Madison Dearborn Capital Partners III, L.P., by Madison Dearborn Partners III, L.P., its General Partner, by Madison Dearborn Partners, LLC, its General Partner, by Mark B. Tresnowski, its Managing Director   04/20/2007
**Signature of Reporting Person Date
 /s/ PCA Holdings LLC, by Madison Dearborn Capital Partners III, L.P., its Managing Member, by Madison Dearborn Partners III, L.P., its General Partner, by Madison Dearborn Partners, LLC, its General Partner, by Mark B. Tresnowski, its Managing Director   04/20/2007
**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) Reflects a pro rata distribution of shares of common stock of the issuer by PCA Holdings LLC ("Holdings"), the record and direct beneficial owner of the shares, to its two members, Madison Dearborn Capital Partners III, L.P. ("MDCP III") and a fund affiliated with MDCP III (collectively, the "Funds") on April 20, 2007, which shares were further distributed pro rata (i) by the Funds to their respective general and limited partners on that date, including Madison Dearborn Partners III, L.P. ("MDP III"), the sole general partner of MDCP III and the fund affiliated with MDCP III, and (ii) by MDP III to its partners on that date.
(2) Holdings is the record and direct beneficial owner of 6,773,010 shares. The shares held by Holdings may be deemed to be beneficially owned by MDCP III, the managing member of Holdings, and a fund affiliated with MDCP III. In addition, securities over which MDCP III has voting and dispositive power may be deemed to be beneficially owned by MDP III. John A. Canning, Paul J. Finnegan and Samuel M. Mencoff are the sole members of a limited partner committee of MDP III that have the power, acting by majority vote, to vote or dispose of the shares directly held by MDCP III. Messrs. Canning, Finnegan and Mencoff and MDP III each hereby disclaims any beneficial ownership of any shares over which MDCP III has voting and dispositive power. Due to this limited partner committee of MDP III, Madison Dearborn Partners, LLC, the sole general partner of MDP III, no longer reports beneficial ownership of shares which may be beneficially owned.
(3) MDP III, MDCP III and the fund affiliated with MDCP III each hereby disclaims any beneficial ownership of any shares directly held by Holdings, except to the extent of such reporting person's pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of the reported shares for purposes of Section 16 or for any other purpose.

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