This book constitutes the refereed proceedings of the First International 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 were carefully reviewed and selected from numerous submissions and focus on analytical models based on game, information, communication, optimization, decision, and control theories that are applied to diverse security topics. The papers are organized in topical sections on security investments and planning, privacy and anonymity, adversarial and robust control, network security and botnets, authorization and authentication, as well as theory and algorithms for security.