This observational study sought to improve our understanding of factors that contribute to risky sexual behavior among women seeking treatment for alcohol and other substance use disorders. Women were recruited at the start of outpatient (n=236) or inpatient (n=166) treatment. At intake, a Timeline Follow-back interview was used to obtain retrospective reports of daily drinking, drug use, and sexual behavior for a 90-day pre-treatment baseline period. Additional interview and questionnaire measures also were obtained. Measures were re- administered at four 90-day follow-up interviews. Among women who reported sex with a primary partner during baseline (n=261), 15% reported consistent condom use for all events with this partner, whereas 80% reported no condom use with this partner. Among women who reported sex with a non-primary partner (n=159; doesn’t include commercial sex trading), 26% reported consistent condom use and 45% reported no condom use with such partners. Significant correlates of non-use of condoms included negative beliefs and attitudes and low self-efficacy regarding condom use and AIDS prevention, as well as psychological distress, sexual impulsiveness and sensation seeking, history of severe assault by a male partner, and (with primary partners) negative partner attitudes toward condom use. Some of these correlates also predicted unprotected sex with a primary partner during the first 90 days after treatment entry, after controlling for baseline. However, unsafe sex with a non-primary partner during follow-up was most notably associated with follow-up levels of substance use, i.e., more drinks per drinking day and greater frequency of alcohol, marijuana, and cocaine use. In sum, preliminary analyses of baseline and follow-up data indicate a high prevalence of unprotected sex in this population. Identification of factors related to baseline and follow-up levels of risky behavior may suggest targets for future intervention development.