OBJECTIVE. Emerging evidence about optimal youth development highlights the importance of both reducing negative behavior and promoting positive behavior. In our study we tested a contextual model derived from positive youth-development theory by examining the association of family, school, and community risk and promotive factors, with several outcome indices of both positive and negative adolescent development. METHODS. A sample of 42305 adolescents aged 11 to 17 (51% girls) was drawn from the 2003 National Survey of Children's Health. Survey item composites were formed representing promotive and risk factors in the family (eg, closeness, aggression) and school and community (eg, community connectedness, school violence). Outcome composites reflected positive (social competence, health-promoting behavior, self-esteem) and negative (externalizing, internalizing, academic problems) developmental outcomes. Ordinary least squares regression was used to test the overall model. RESULTS. Between 0.10 and 0.50 of the variance in each outcome was explained by the contextual model. Multiple positive family characteristics were related to adolescent social competence and self-esteem, as well as lowered levels of internalizing and externalizing behavior and academic problems. Family communication, rules about television, and parents' own healthy behavior were related to adolescent health-promoting behavior. School and community safety were associated with increased social competence and decreased externalizing behavior. School violence was related to adolescent internalizing and externalizing behavior, as well as academic problems and lower self-esteem. CONCLUSIONS. Our results support the proposition that healthy adolescent development has roots in multiple contexts. Youth who were involved in contexts that provided positive resources from important others (ie, parents, schools, and communities) not only were less likely to exhibit negative outcomes, but also were more likely to show evidence of positive development. These findings provide important implications for intervention and prevention efforts and, more generally, for the promotion of positive, competent, and healthy youth development.