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

Pioneer Southwest Energy Partners L.P. (“Pioneer Southwest”) (NYSE:PSE) today announced its second quarter 2010 earnings press release is scheduled to be issued after the close of trading on the New York Stock Exchange on Wednesday, July 28, 2010.

A conference call is scheduled for Thursday, July 29, 2010 at 11:30 a.m. CT to discuss the second quarter results. Instructions on how to listen to the call and view the accompanying presentation are shown below.

         

Internet: www.pioneersouthwest.com

Select “Investors,” then “Earnings Calls & Webcasts” to listen to the discussion and view the presentation.   Telephone: Dial (888) 349-9587 confirmation code: 1462241 five minutes before the call to listen to the discussion. View the presentation via Pioneer Southwest’s internet address above.

A replay of the webcast will be archived on Pioneer Southwest’s website. A telephone replay will be available through August 20 by dialing (888) 203-1112, confirmation code: 1462241.

Pioneer Southwest is a Delaware limited partnership headquartered in Dallas, Texas, with current production and drilling operations in the Spraberry field in West Texas.

Special Notice Regarding Pioneer Natural Resources Company Second Quarter Earnings Call. On Thursday, July 29, 2010 at 10:00 a.m. CT, Pioneer Natural Resources Company (“PNRC”) will conduct its second quarter 2010 earnings conference call and webcast. Pioneer Southwest was formed by PNRC to own and acquire oil and gas assets in Pioneer Southwest’s area of operations. As such, it is possible that discussion on the PNRC call will include matters regarding Pioneer Southwest. To listen to the PNRC call, dial (888) 298-3457 confirmation code: 2458806 five minutes before the call. The accompanying presentation can be viewed at www.pxd.com. Select “Investors,” then “Earnings Calls & Webcasts” to listen to the discussion and view the presentation. A replay of the webcast will be archived on PNRC’s website. A telephone replay will be available through August 20 by dialing (888) 203-1112, confirmation code: 2458806.