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 *
  PIONEER NATURAL RESOURCES CO
 2. Date of Event Requiring Statement (Month/Day/Year)
04/29/2008		 3. Issuer Name and Ticker or Trading Symbol
Pioneer Southwest Energy Partners L.P. [PSE]
(Last)
(First)
(Middle)
5205 N. O'CONNOR BLVD, SUITE 200		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
_____ Officer (give title below) __X__ Other (specify below)
Indirect Owner of GP
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

IRVING, TX 75039		 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)
No securities beneficially owned 0 (1)
D
 

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
PIONEER NATURAL RESOURCES CO
5205 N. O'CONNOR BLVD, SUITE 200
IRVING, TX 75039		       Indirect Owner of GP
PIONEER NATURAL RESOURCES USA INC
5205 N. O'CONNOR BLVD., SUITE 200
IRVING, TX 75039		       Direct Owner of GP

Signatures

Mark H. Kleinman, Vice President 04/29/2008
**Signature of Reporting Person Date
Mark H. Kleinman, Vice President 04/29/2008
**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) This Form 3 is being filed in connection with the effectiveness of the Issuer's Registration Statement on Form S-1 (Registration No. 333-144868) initially filed with the Securities and Exchange Commission on September 13, 2007, as amended.

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

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.