College students' risky sexual behavior places them at relatively higher than average risk for HIV infection. This study examines various explanations for college students' risky behavior, and proposes and tests a model of factors influencing college students' sexual behavior. A LISREL estimation of the model shows that the model fits the data. The results also show that (1) sensation-seeking predispositions and the sexual motive for a pleasurable relationship are indirectly or directly related to all measures of sexual behavior (i.e., number of partners, incidence of unprotected sex, and percentage of condom use); (2) sexual motives driven by concern for health have only an indirect effect on percentage of condom use; and (3) optimistic bias, personal relevance, perceptions about partners, and images of condoms are related to sensation seeking, sexual motives, and sexual behavior. In addition, interpersonal influence from sexual partners appears to both facilitate and inhibit safer sexual behavior. Suggestions are provided regarding campaigns designed for AIDS prevention among college students.