The major goal of this study is to evaluate the short-term and long-term effectiveness of three procedures on preventing the emergence of serious antisocial behavior in 8-15 year old high risk children. The children studied will be 3200 predominantly African-American (40%) and Hispanic (40%) male and female children in two urban communities with serious crime rates approximately three times the national average (Chicago and Aurora, Illinois). A high-risk subsample of 800 children will be identified using multiple gating. The prevention procedures are: (1) a general enhancement classroom-based social-cognitive and teacher training program; (2) the general enhancement program plus and intensive peer-focused social- cognitive training program for targeted high-risk children only; and (3) the general enhancement classroom program plus the peer-focused training plus a family relations intervention for targeted high-risk children and their families. Our strategy for preventing the emergence of serious antisocial behavior is to target relevant aspects of one or more microsystem contexts (classroom, peers, family) which have been shown empirically to be most influential in the development of antisocial behavior. In addition, our objective is not only to test whether the interventions affect behavior, but to determine through what psychological mechanisms they exert their major effects. In order to accomplish this, it is proposed to conduct a three-year program of research involving three waves of assessment and two periods of intervention. During the first year, screening measures and the first wave of assessment on most measures will be completed for all subjects. The intervention procedures will be further developed in coordination with consultants, teachers, and local community representatives. A particular concern is to develop culturally- relevant prevention programs for urban minority children. During the second year, the 20 week intervention and subsequent testing will be conducted. This procedure will be repeated in year 3.