In this article, we integrate cultural evolutionary theory with empirical research from developmental psychology, cultural anthropology, and primatology to explore the role of peer learning in the development of complex instrumental skills and behavioral norms. We show that instrumental imitation, contingent teaching, generative collaboration, and selective copying contribute to domain-specific transmission of knowledge between peers. Stages of development and characteristics inherent to the learner and model influence how and when children learn from each other. Peer learning is persistent across societies despite cultural beliefs that favor adult-child transmission in some settings. Comparative research hints at the possibility that children's greater motivation to interact with and learn from each other may set humans apart from other primates. We conclude by outlining avenues for future research, including how individual characteristics and developmental changes in social networks, motivation, and cognition may contribute to cultural evolution.