Peer Group Effect on the Development of Adolescents' Problem Behaviors and Depression: Moderating Effects of Group Membership Stability.

PURPOSE: This study investigated peer group socialization of problem behaviors and depression during early adolescence. The research specifically examined how the stability of group membership moderates the relationship between group-level behaviors and individual outcomes. METHODS: A six-month longitudinal design was employed, involving 2526 Grade 7 students. The social cognitive map and multilevel modeling were used to identify peer group structures and analyze behavioral trajectories over time. RESULTS: Peer groups demonstrated high stability, as 80% of groups maintained at least 50% of their membership and 42% maintained at least 70%. Longitudinal analysis revealed that individual depressive symptoms predicted an increase in problem behaviors for both genders. However, the reverse path (problem behaviors predicting depression) was significant only for boys. Regarding socialization, the average problem behaviors of a peer group significantly predicted an increase in individual problem behaviors for girls, regardless of group stability. For boys, this socialization effect was limited to those in highly stable groups. No evidence of peer group socialization was found for depressive symptoms in either gender. CONCLUSION: Early adolescent peer groups are stable social environments that primarily influence problem behaviors rather than depressive symptoms. The impact of peer socialization is gender-specific and, for boys, contingent upon the stability of their peer groups.