Humans in every culture judge some actions and people as positive, others as negative. It is clearly beneficial to distinguish supportive and friendly individuals from harmful and malicious ones, and evolutionary biologists, comparative psychologists, and cultural anthropologists have argued that an ability to evaluate others is essential for navigating the social world. This project will explore the developmental origins of social evaluation; specifically, how infants and toddlers (a) understand and predict how other individuals evaluate social actions and the agents who perform them; and (b) form their own positive and negative attitudes towards agents based on the actions that they engage in. The study also explores the extent to which young children's social evaluations are explicitly available, using verbal judgments and choices of whom to reward or punish and explores how children's social evaluation of an individual influences their willingness to learn from that individual. Learning more about the nature and development of social evaluation will increase understanding of atypical development of these processes in, for example, individuals with autism and Asperger's syndrome.