The Moderating Role of Developmental Microsystems in Selective Preventive Intervention Effects on Aggression and Victimization of Aggressive and Socially-Influential Students

Although ecology is often cited as an important factor in prevention, it is infrequently incorporated to the evaluation of intervention effects. This study tests the moderating role of three developmental microsystems (family, peer, and school) on a family-focused intervention to prevent violence. The family intervention was part of the Multisite Violence Prevention Project, a trial involving random assignment of 37 schools to four conditions: 1) a universal intervention composed of a student social-cognitive curriculum and teacher training, 2) a selective multiple family group intervention, 3) these two interventions combined, and 4) a no-intervention control condition. The present study focused on 1,113 eligible families from two cohorts. Students attending schools that were randomly assigned to the selective family intervention were compared with students in other conditions. Composite indicators of risk were formulated for each microsystem and entered as moderators of intervention effects on violence and aggression perpetration and overt and relational victimization. Results of intent-to-treat and dose-weighted analyses indicated that peer risk moderated outcomes, but family and school risk did not. Intervention effects were limited to youth with elevated peer risk at the outset of intervention. This pattern points to the importance of peer groups in the effects of family-focused interventions, particularly with high-risk early adolescent youth. More generally, the results illustrate the importance of mesosystems for understanding prevention effects.