Examination of Peer–Group Contextual Effects on Aggression During Early Adolescence

Peer group contextual effects of aggressive behavior among middle school students (6th-8th graders) were examined using a short-term longitudinal design. More specifically, the homophily hypothesis that peer group membership influences individual-level bullying and fighting was evaluated with multilevel sex-specific models of individual- and peer-level aggression scores. Peer groups were identified via social network analysis. Intraclass correlation coefficients yielded through hierarchical linear modeling demonstrated substantial within-group similarity on self-reported bullying and fighting, suggesting that students affiliate with individuals who bully and fight at the same frequency. Peer group bullying and…