 The proposed study will be guided by four aims. AIM 1 is to evaluate the effectiveness of Familias Unidas, relative to Community Practice i.e., standard prevention services, in preventing illicit drug use in a community sample of Hispanic adolescents; AIM 2 is to evaluate the effectiveness of Familias Unidas, relative to Community Practice in preventing cigarette use in a community sample of Hispanic adolescents; AIM 3 is to evaluate the effectiveness of Familias Unidas, relative to Community Practice, in preventing unsafe sexual behavior in a community sample of Hispanic adolescents; and AIM 4 is to assess the extent to which family functioning mediates the effects of the intervention on illicit drug use, cigarette use, and unprotected sexual behavior. 