This study will examine the relationships among alcohol and drug use, high-risk sexual behavior, and HIV seropositivity in alcohol- dependent populations. The University of California, San Francisco will collaborate with the San Francisco Department of Public Health to conduct one prospective cohort study and three cross-sectional surveys of predominantly heterosexual and racially mixed alcoholics and problem drinkers entering treatment programs over a five-year period. The emphasis is on those seeking treatment because (1) they are a large population, (2) they may be at high risk (though this needs to be determined), and (3) they are readily accessible for public health interventions. A cohort of 1250 men and women aged 18-44, drawn from five San Francisco alcohol treatment centers in 1989-90, will be examined cross-sectionally and then re-examined after 1 and 3 years of follow-up. Two additional samples of 1250 subjects each will be examined cross-sectionally, one in 1991-2 and the other in 1993- 94. In each of these samples, the subjects will be approximately 81% men and 91% heterosexual. Because of the increased risk in the Black and Hispanic populations, these groups will be oversampled in order to obtain similar precision in the Black, Hispanic, and white strata; approximately 33% of the subjects will be Black, 25% Hispanic, 37% white, and 5% of another ethnicity. Respondents will be tested for HIV antibodies, and will be interviewed to assess the prevalence and predictors of high-risk sexual activity and seropositivity. Subjects in the prospective cohort, all of whom will have received AIDS risk-reduction education as well as treatment for alcoholism, will be followed for the 3-year incidence of seroconversion, for changes in risk behaviors such as unprotected intercourse with high-risk partners, and for the antecedents of these events such as AIDS knowledge, attitudes and beliefs. Subjects in the multiple cross-sectional component of the study will reveal changes in the prevalence of seropositivity, of risk behaviors, and of knowledge, attitudes and beliefs about AIDS in populations of alcoholics and problem drinkers as they present for treatment over the next five years. In summary, the prospective cohort component will provide data on trends in alcoholics and problem drinkers who have received education and treatment, and the multiple cross-sectional component will provide data on trends in the untreated alcohol population of the United States. These studies will reveal the rates of high- risk behavior and HIV infection in these populations, and provide a basis for designing appropriate and effective interventions for alcohol treatment settings.