PSE Pioneer Southwest Energy Partners L.P. Pioneer Southwest Energy Partners Lp

Pioneer Southwest Energy Partners L.P. (�Pioneer Southwest�) (NYSE:PSE) announced today a cash distribution of $0.31 per unit on Pioneer Southwest's outstanding common units for the quarter ended June 30, 2008. The distribution is payable August 12, 2008 to unitholders of record at the close of business on July 29, 2008. This distribution reflects an annual distribution rate of $2.00 per common unit, pro rated from the May 6, 2008 closing date of Pioneer Southwest�s initial public offering through June 30, 2008. Pioneer Southwest is a Delaware limited partnership formed by Pioneer Natural Resources Company to own and acquire oil and gas assets in its area of operations. This area includes onshore Texas and eight counties in the southeast region of New Mexico.