Pioneer Southwest Energy Partners L.P. (“Pioneer Southwest”) (NYSE:PSE) today announced its third quarter 2012 earnings press release is scheduled to be issued after the close of trading on the New York Stock Exchange on Wednesday, October 31, 2012. A conference call is scheduled for Thursday, November 1, 2012 at 11:00 a.m. CT to discuss the third 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) 455-2260 confirmation code: 2684624 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 November 26 by dialing (888) 203-1112, confirmation code: 2684624. 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 Third Quarter Earnings Call: On Thursday, November 1, at 9:00 a.m. CT, Pioneer Natural Resources Company (“PNRC”) will conduct its third quarter 2012 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) 296-4217 confirmation code: 4877153 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 November 26 by dialing (888) 203-1112, confirmation code: 4877153.