This book constitutes the refereed proceedings of the FirstInternational Conference on Decision and Game Theory for Security, GameSec 2010, held in Berlin, Germany, in November 2010.The 12 revised full papers and 6 revised short papers presented werecarefully reviewed and selected from numerous submissions and focus onanalytical models based on game, information, communication, optimization, decision, and control theories that are applied to diversesecurity topics. The papers are organized in topical sections onsecurity investments and planning, privacy and anonymity, adversarialand robust control, network security and botnets, authorization andauthentication, as well as theory and algorithms for security.