Social developmentalists typically distinguish three levels of analysis in the study of peer relations in childhood and adolescence: individual, dyadic, and group. At the individual level of analysis, sociometric status and individual social behavior are studied. At the dyadic level, researchers traditionally study friendships but increasingly also other types of relationships such as enemies, mutually aggressive dyads, bully-victim pairs, and romantic relationships. The objects of study at the group level of analysis are the social networks, groups, and cliques to which children and adolescents belong. The phenomena at each of these three levels are uniquely affected by and have unique effects on social development. Although the importance of all three levels for the understanding of the developmental significance of peer relations has been recognized, there is relatively more research at the individual and dyadic levels of analysis than at the group level. The chapters in this volume correct this trend. They make significant contributions to the study of peer relations at the group level through detailed examinations of children's social networks. In this article, the author discusses some of the reasons why peer relations researchers may have studied social networks less frequently than individuals and dyads and how the chapters of this volume counteract this trend. In addition, the contributions to this volume exemplify several developments in peer relations research. The author also outlines these recent developments and demonstrates how the chapters reflect them.