Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF 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 *
  Warburg Pincus Private Equity IX, L.P.
 2. Date of Event Requiring Statement (Month/Day/Year)
02/27/2006		 3. Issuer Name and Ticker or Trading Symbol
Builders FirstSource, Inc. [BLDR]
(Last)
(First)
(Middle)
C/O WARBURG PINCUS LLC, 466 LEXINGTON AVENUE		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

NEW YORK, NY 10017		 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 Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock, par value $0.01 per share 8,652,551.5 (1)
I (1)
By Building Products, LLC (1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Warburg Pincus Private Equity IX, L.P.
C/O WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 10017		     X    
Warburg Pincus IX LLC
C/O WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 10017		     X    
Warburg Pincus Partners LLC
C/O WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 10017		     X    
WARBURG PINCUS LLC
C/O WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 10017		     X    
WARBURG PINCUS & CO
C/O WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 100173147		     X    
KAYE CHARLES R
C/O WARBURG PINCUS LLC
466 LEXINGTON AVE
NEW YORK, NY 10017		     X    
LANDY JOSEPH
C/O WARBURG PINCUS LLC
466 LEXINGTON AVE
NEW YORK, NY 10017		     X    

Signatures

/s/ Scott A. Arenare, Warburg Pincus Private Equity IX, L.P., by Warburg Pincus IX LLC (General Partner), by Warburg Pincus Partners LLC (Sole Member), by Warburg Pincus & Co. (Managing Member), by Scott A. Arenare (Partner) 03/03/2006
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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) See Exhibit 99.1.
 
Remarks:
Exhibit List:

Exhibit 24.1 - Power of Attorney for Joseph P. Landy
Exhibit 24.2 - Power of Attorney for Charles R. Kaye
Exhibit 99.1 - Explanation of Responses
Exhibit 99.2 - Joint Filers' Names and Addresses
Exhibit 99.3 - Joint Filers' Signatures

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

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