This study seeks to investigate the efficacy and mechanisms of a highly promising "Culturally Informed Family Therapy for Adolescents" in preventing the emergence of two important health disparities in Hispanic youth, namely drug use & HIV and other sexually transmitted infections (STI). The proposed study is submitted as part of a P60 application entitled "NCMHD Center for Culturally-Tailored Hispanic Health Disparities Research (El Centro)", in response to the NIH RFA-MD-06-002: Establishing Comprehensive NCMHD Research Centers of Excellence.