 Until recently, epistemology—the study of knowledge and justified belief—was heavily individualistic in focus. The emphasis was on evaluating doxastic attitudes (beliefs and disbeliefs) of individuals in abstraction from their social environment. Social epistemology seeks to redress this imbalance by investigating the epistemic effects of social interactions and social systems. After giving an introduction, and reviewing the history of the field in sections 1 and 2, we move on to discuss central topics in social epistemology in section 3. These include testimony, peer disagreement, and judgment aggregation, among others. Section 4 turns to recent approaches which have used formal methods to address core topics in social epistemology, as well as wider questions about the functioning of epistemic communities like those in science. In section 5 we briefly turn to questions related to social epistemology and the proper functioning of democratic societies. 