Securing complex and networked systems has become increasingly important as these systems play an indispensable role in modern life at the turn of the – formation age. Concurrently, security of ubiquitous communication, data, and computing poses novel research challenges. Security is a multi-faceted problem due to the complexity of underlying hardware, software, and network inter- pendencies as well as human and social factors. It involves decision making on multiple levels and multiple time scales, given the limited resources available to both malicious attackers and administrators defending networked systems. – cision and game theory provides a rich set of analyticalmethods and approaches to address various resource allocation and decision-making problems arising in security. This edited volume contains the contributions presented at the inaugural Conference on Decision and Game Theory for Security – Game Sec 2010. These 18 articles (12 full and 6 short papers) are thematically categorized into the following six sections: – "Security investments and planning" contains two articles, which present optimization methods for (security) investments when facing adversaries. – "Privacy and anonymity" has three articles discussing location privacy, – line anonymity, and economic aspects of privacy. – "Adversarial and robust control" contains three articles, which investigate security and robustness aspects of control in networks. – "Networksecurityandbotnets"hasfourarticlesfocusingondefensivestra- giesagainstbotnetsaswellasdetectionofmaliciousadversariesinnetworks. – "Authorizationandauthentication"hasanarticleonpasswordpracticesand another one presenting a game-theoretic authorization model. – "Theory and algorithms for security" containsfour articles on various th- retic and algorithmic aspects of security.