Reasoning about the knowledge and beliefs of a single agent or group of agents is an interdisciplinary concern spanning philosophy, game theory, artificial intelligence, and mathematics. This course will introduce students to key issues that arise when designing a formalism to make precise intuitions about the knowledge and beliefs of a group of agents. Topics to be discussed include modal logics of knowledge and beliefs (including probabilistic modal logics), formal definitions of common knowledge and common belief, dynamic epistemic logic, modal logics of belief revision, logical omniscience, the surprise examination paradox, the knowability paradox, the absent-minded driver problem, and Aumann's agreeing to disagree theorem.