This experiment examined the effects of alcohol on women's sexual decision making during a laboratory social interaction with a potential dating partner. Participants completed an assessment of sex-related alcohol expectancies, were randomly assigned to consume alcohol, no alcohol, or a placebo, and then interacted with a male confederate. Stronger sex-related alcohol expectancies and actual alcohol consumption significantly increased women's sexual relationship interest in their interaction partner, which in turn was associated with lower ratings of partner sexual risk. Lower ratings of partner sexual risk predicted increased intention to engage in unprotected sex. These findings demonstrate alcohol consumption's causal effects on sexual risk judgments made during analogue social interactions, delineate the indirect effects of alcohol expectancies and alcohol consumption on sexual risk decisions, and provide support for a Cognitive Mediation Model of women's sexual decision making. These findings can inform empirically based intervention programs designed to reduce the sexual risk taking of women. (Contains 2 figures.)