Although not limited to school contexts, bullying perpetration and victimization often emanates from social ecologies formed within the classroom. Thus, to fully illuminate risk for involvement in bullying, we must investigate contextual features of schools that heighten or minimize aggression among students and the targeting of children for peer victimization. To this end, the articles in this special section each contribute conceptually and empirically to the study of school-related factors in bullying and peer victimization. This introduction summarizes and highlights the major findings of each paper, organized around two major themes of the articles—the role of peer group ecologies and the role of the classroom teacher. We conclude our synopsis by discussing implications for intervention and the need for anti-bullying efforts that systemically address the peer group and teacher influences identified in these investigations.