This book constitutes the thoroughly refereed post-conference proceedings of the Third International Conference on Game Theory for Networks (GameNets 2012) held in Vancouver, Canada, May 24-26, 2012. The 13 revised full papers were carefully selected from 24 submissions and are presented together with 7 invited papers. The papers focus on topics such as mechanism design, physical layer games, network mechanisms, stochastic and dynamic games, game-theoretic network models, cooperative games in networks, security games, spectrum sharing games, P2P and social networks and economics of network QoS.