First published in 1997, Primate Cognition was a groundbreaking and highly successful book that set the agenda for a new field of study. This second edition provides an extended and up-to-date survey of the field, divided into two volumes. Existing areas of research are updated with the latest findings, and there are several areas of research that for all practical purposes did not exist at the time of the first edition, for example, on prosocial behavior, behavior in social dilemmas, and metacognition.