Juvenile detainees comprise a population that engages in high-risk behavior. This study examined sexual risk and substance use behavior and the perceptions of African American female adolescent detainees (N = 765) regarding the influence of alcohol and marijuana use on their social and sexual behaviors. Overall, 58% and 64% reported alcohol and marijuana use, respectively. Alcohol's perceived influence on sexual behavior (p < .001) was significantly different between those who drank and those who did not; marijuana's influence on social (p < .01) and sexual (p < .001) behavior was significantly different between those who used marijuana and those who did not. There is a need for further study of the influence of substance use on social and sexual behavior among African American female adolescent detainees.