We propose to investigate correlates of sexual risk and sexually transmitted infections (STIs) among female methamphetamine (MA) users in San Francisco, CA. While prevalent on the West Coast for decades, MA use is a rapidly growing problem nationwide. These trends have sparked intensive exploration of associations between MA use and sexual risk among gay and bisexual men. However, less is known about MA use among women, even though they represent 40% of MA treatment admissions in the United States. The handful of studies that have explored HIV risk among female MA users have found a high prevalence of sexual risks, including unprotected anal and vaginal intercourse, multiple sexual partners, and sex work. The proposed study seeks to establish a more comprehensive understanding of female MA users and the factors associated with sexual risk among them, using quantitative and qualitative methods. We will use the social ecological model of health to frame the investigation in terms of individual, interpersonal, structural, and cultural factors that affect sexual risk among female MA users. Specific Aims are: Aim 1: To determine what individual-level factors (patterns of MA use, polydrug use, psychological morbidities, and other factors) are associated with sexual risk among female MA users. Aim 2: To determine what interpersonal-level factors (partner type, intimate relationship characteristics, dependent children) are associated with sexual risk among female MA users. Aim 3: To determine what structural-level factors (homelessness, incarceration, venues of sex and drug use) are associated with sexual risk among female MA users. Aim 4: To determine what cultural-level factors (race/ethnicity, gender norms, religion) are associated with sexual risk among female MA users. The quantitative component will consist of a cross-sectional study of 400 female MA users recruited over 2 years using targeted sampling methods. Study participants will be interviewed and screened for STIs (gonorrhea, chlamydia, herpes, and syphilis) and HIV. The qualitative component will investigate in detail the context and circumstances of specific sexual risks by interviewing 50 female MA users. The final phase of the proposed research will synthesize the quantitative and qualitative findings to yield recommendations for gender-specific and culturally appropriate interventions at the individual, interpersonal, and structural levels. The proposed study addresses an understudied and important public health issue: MA use among women. [unreadable] [unreadable] [unreadable]