Recent theoretical approaches to children and childhood studies have viewed children and their peer cultures as worthy of documentation and study in their own right. Childhood sociologist William Corsaro defines peer culture as a stable set of activities, artifacts, values, and concerns that children engage in and share in interaction with their peers. It has been suggested that one fundamental feature of peer talk and social interactions is their co-constitutive relation to the shared worlds of childhood culture, and that peer interactions can be seen as a major resource in cultural and relational work. Peer group studies diverge from tradition psychological research by focusing on children’s social practices and examining how children use cultural resources to build their social worlds, which can be very different from the life worlds of adults. By being together and spending time with their peers, children contribute to the establishment of peer cultures. According to Corsaro, they engage in creative appropriation and interpretive reproduction, rather than individual internalization of adult culture. Such appropriation is creative in that it both extends or elaborates peer culture and simultaneously contributes to the reproduction and extension of the adult world. For instance, in educational settings, children transform institutional norms and values by producing secondary adjustments, that is, actions by which they comply with the institutional norms and simultaneously exploit these norms for their own purposes. This entry examines children’s peer interactions and social organization, children’s play, and their gender differences, and considers some future directions for research.