This course is a general introduction to game theory with a special focus on the growing body of literature on epistemic game theory. Epistemic game theory aims at formalizing assumptions about knowledge, belief and rationality, and then studies their behavioral implications in games. One standard assumption is that there is common belief of rationality among all the relevant players. A second, related, assumption is adeptly summarized by Robert Aumann and Jacques Dreze in a recent article (Rational Expectations in Games, American Economic Review, 98 (2008), pp. 72-86): ""the fundamental insight of game theory [is] that a rational player must take into account that the players reason about each other in deciding how to play"". Exactly how the players (should) incorporate the fact that they are interacting with other (actively reasoning) agents into their own decision making process is the subject of much debate. The course will focus on formal models of strategic reasoning in game-theoretic situations. Some previous exposure to game and decision theory will be helpful, but is not required (I will do my best to provide the necessary background in game and decision theory. This will include a tutorial on the basic concepts of game and decision theory during the first lecture and additional lectures on background material as needed during the course). This is an interdisciplinary topic, and so our readings will be taken from economics, logic, philosophy and cognitive science journals.