Most theoretical models of HIV risk behavior have not considered the role of personality factors, and few studies have examined mechanisms accounting for dispositional influences on sexual risk taking. This study elaborated on a conceptual model emphasizing sexual sensation seeking, alcohol expectancies, and drinking before sex as key predictors of HIV risk (S. C. Kalichman, L. Tannenbaum, & D. Nachimson, 1998). Multiple groups structural equation modeling was used to determine whether gender moderated relationships among these variables in a sample of 611 heterosexual, young adult drinkers (49% women, 76% Caucasian, mean age = 25 years). The model provided an excellent fit to the data, and gender differences were not substantiated. Sexual sensation seeking predicted HIV risk directly as well as indirectly via sex-related alcohol expectancies and drinking in sexual contexts. Findings suggest that expectancies and drinking before sex represent proximal mechanisms through which dispositional factors influence sexual risk outcomes. Moreover, these relationships appear to be similar in men and women. Interventions could benefit from targeting alcohol expectancies and drinking before sex in individuals with a dispositional tendency toward sexual risk taking.