Findings suggest that interventions with African-American families might continue to benefit from targeting parental monitoring of peers to help ameliorate externalizing behaviors among delinquent adolescents. Findings in the Hispanic sample support the importance of family function (family conflict, parenting practices) when investigating the development of externalizing behavior and marijuana use among Hispanic adolescents. Parental monitoring of peers did not play a pivotal role in mediating the relationship between family functions and adolescent problem behaviors among a clinical sample of African-American and Hispanic adolescents and their families; with one exception, the mediating role of parental monitoring of peers on the relationship between family functioning and externalizing behavior among the full sample of adolescents, no comparable results were found for marijuana use, for sexual risk behaviors, or among each racial and ethnic sample. For African-American participants, family functioning was not related to parental monitoring of peers, but parental monitoring of peers was related to externalizing behavior. In contrast, among Hispanic families, family functioning was related to parental monitoring of peers, but parental monitoring of peers was not related to externalizing behavior. Therefore, only in the full sample were significant relations detected between both family functioning and parental monitoring of peers, and parental monitoring of peers and externalizing behavior and the mediating effect of peer monitoring of peers. Explanations for the findings might include family systemic dysfunction (poor communication and relations between adolescents and their parents, poor general parental monitoring and parental monitoring of peers, and minimizing and denial of problem behaviors by family members) which may have led to large discrepancies; adolescents self-reported the assessments of their families’ level of function, their parents’ monitoring of peers, and their sexual risk behaviors and marijuana use. Parent guardians self-reported levels at which they monitored their children’s peers and reported on their children’s externalizing behavior. Tables, references, appendix