Low income minority urban youth have been identified as a group for whom there is current concern about HIV transmission. The aim of this study was to evaluate AIDS knowledge, perception of risk, and risk behaviors related to sex in a sample of urban, low income, African American and Hispanic adolescents and young adults. The study was conducted between February and July of 1991. Data were obtained from a household probability sample of 1,435 individuals. Completed interviews included 726 African American (324 males, 402 females) and 709 Hispanic (359 males, 350 females) adolescents and young adults from low income areas of Detroit, Michigan. The data set contains 1,106 variables. Interviewers were hired and trained specifically for the study. Over 95% of the 60 interviewers employed were minority residents of Detroit. Interviewer training consisted of instruction of general interviewing techniques, as well as instruction relevant to obtaining drug and sexual histories. The study questionnaire was developed through pilot testing using open-ended questions, consultation with youth and youth service providers, and formal pre-testing. The final questionnaire consisted of close-ended questions and required about one hour to administer. About 108 of the interviews were conducted using a Spanish language questionnaire. The questionnaire assessed general knowledge of AIDS transmission; knowledge of routes of sexual transmission (both heterosexual and homosexual); respondents' sexual behavior, number of sexual partners, and condom use; and perceived susceptibility to AIDS infection.