Abstract
Peer relationships are a major part of youths’ experiences at school. Moreover, both close friendships and peer group affiliations are related to student engagement in school. This chapter reviews research on school belonging, friendships, and negative social experiences (e.g., rejection or bullying) as related to engagement, with discussion of effects of peer relationships for youth from historically underrepresented backgrounds. Across these sections, research on both academic and extracurricular engagement is reviewed to understand if peer relationships operate in similar ways across these two domains. The chapter concludes with a discussion of areas for future research and implications for policy and practice, with consideration of existing policies that can restrict peer relationships (e.g., academic tracking or selection of participants in extracurricular activities).