The delinquency of female adolescents at risk has increased conspicuously, much to the concern of human service and public health practitioners. Nevertheless, prior findings of pertinent research have commonly been based on samples of male or gender-mixed participants, especially general youths in the community. These cannot adequately explicate the impacts of different contextual systems on at-risk female adolescents, who are, in fact, more vulnerable to developing delinquency. Based on cross-sectional data collected from a sample of 236 at-risk female adolescents with the help of a large social work organization, the present study investigated and compared the effects of family, school, and peer systems on different forms of delinquency among at-risk female adolescents. The results show that positive family functioning, constructive school experiences, and deviant peer influence were predictive of both self-destructive and other-destructive delinquency in at-risk adolescent girls, respectively, but the effects were significantly different depending on which contextual systems influenced what forms of delinquency. Furthermore, the relationships between positive family functioning and both forms of delinquency were significantly mediated by the effects of constructive school experiences and deviant peer influence, giving support to the distal role of family and the proximal functions of school and peers in adolescence. Implications for policy prevention and interventions to strengthen the contextual supports in different social systems to help female adolescents at risk are discussed.