A history of alcohol and marijuana use was found to be common among the African-American female adolescent detainees in this study. Over half reported lifetime alcohol (58 percent) or marijuana (64 percent) use. These high levels of substance use were a concern not only because they were illegal activities, but because they could contribute to other risk behaviors, including high-risk sexual situations. In addition, there were consistent relationships concerning beliefs that alcohol or marijuana influenced the way they behaved in social situations or in sexual situations. Overall, the data indicates that marijuana use was significantly associated with the detainees' social and sexual behavior, whereas alcohol use was significantly associated only with social behavior. African-American female adolescent detainees need to become a major focus of concern. Further study was recommended on the influence of substance use on social and sexual behavior among African-American female adolescent detainees. Tables and references