This article discusses the effectiveness of a multicomponent intervention designed to disrupt developmental processes associated with conduct problems and peer rejection in childhood. Compared with 41 children randomized to a wait list control condition, 45 children in an intervention condition received a social skills training program. At the same time, their parents participated in an in-home family intervention. Compared with control group children, intervention children demonstrated significant improvements on five of six outcome measures. Differences between the experimental and control groups suggest the programs strengthen children's prosocial behavior, promote their ability to regulate emotions, and increase social contact with peers. Intervention also was associated with significant improvements in classroom comportment and decreases in relational aggression, a measure of coercion in peer relationships. The findings are consistent with those of other programs effective in interrupting risk processes associated with conduct problems in childhood and early adolescence. (Contains 3 tables.)