ACM MobiCom 2009 is the 15th in a series of annual conferences sponsored by ACM SIGMOBILE dedicated to addressing the challenges in the areas of mobile computing and wireless and mobile networking. The MobiCom conference series serves as the premier international forum addressing networks, systems, algorithms, and applications that support the symbiosis of mobile computers and wireless networks. MobiCom is a highly selective conference focusing on all issues in mobile computing and wireless and mobile networking at the link layer and above. MobiCom 2009 will be held in September 20-25, 2009 in Beijing, China.