The PEERS® (Program for Education and Enrichment of Relational Skills) training targets age-appropriate social skills. By the use of homework assignments and parallel parent sessions the generalization of skills enhanced. The results of this randomized controlled trial show that social skills significantly improved, as indicated by both selfand parent reports. However, the significant increase in observed social skills as observed in the PEERS® condition was as large as the increase observed in the active control condition. Further research will target mediators and moderators of treatment effects.