Research on children interacting with each other encompasses a wide variety of specific research interest, including but not limited to a focus on language. In this introduction to an issue of Discourse Studies devoted to the contribution of peer talk to pragmatic development, we define ‘peer talk’ as an interdisciplinary field of inquiry and we critically review literature on the role of peer talk in children’s pragmatic development. We suggest that ‘peer talk’ as a field of inquiry properly encompasses studies of the development of language through peer interaction as well as the ways in which peer talk functions in children’s co-construction of their social and cultural worlds. Research reviewed here suggests that peer talk may be a crucial site for pragmatic development, offering children a wide range of opportunities for mutual learning of interactive as well as linguistic skills. The evidence we review, which comes from the fields of language socialization, second language learning, and child-discourse, highlights two major contextual features of peer talk: (1) its collaborative, multi-party, symmetrical participation structure; and (2) its role in the co-constructed worlds of childhood culture. Finally, we call for research and theorizing that would bridge the gap between developmental and ethnographically-informed approaches to the study of child discourse, in order to ensure that children’s peer talk receives the attention due it as a major site for both the development of discourse skills and the creation of childhood culture.