Pioneer Southwest Energy Partners L.P. (“Pioneer Southwest”) (NYSE:PSE) today announced its fourth quarter 2012 earnings press release is scheduled to be issued after the close of trading on the New York Stock Exchange on Wednesday, February 13, 2013. A conference call is scheduled for Thursday, February 14, 2013 at 11:00 a.m. Central Time to discuss the fourth 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) 556-4997 confirmation code: 7448707 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 March 11 by dialing (888) 203-1112, confirmation code: 7448707. 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 Fourth Quarter Earnings Call: On Thursday, February 14, at 9:00 a.m. Central Time, Pioneer Natural Resources Company (“PNRC”) will conduct its fourth 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 (877) 718-5108 confirmation code: 7431932 five minutes before the call. The accompanying presentation can be viewed at www.pxd.com . Select “Investors,” then “Earnings & 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 March 11 by dialing (888) 203-1112, confirmation code: 7431932.