Results indicate that men are twice as likely to be sexually harassing and three times more likely to be sexually coercive as women. Among men, sexual harassment is predicted by child sexual abuse, hostility, adversarial heterosexual beliefs, and alcohol expectancy, with the latter mediating the effects of aggression. Sexual coercion is predicted by adult sexual victimization and alcohol expectancy, with alcohol expectancy again mediating the effect of aggression. Among women, sexual harassment is predicted by adult sexual victimization, adversarial heterosexual beliefs, aggression, and alcohol expectancy, with aggression mediating the effect of adversarial heterosexual beliefs and alcohol expectancy mediating the effect of aggression. Sexual coercion was predicted by hostile personality, which mediated the effects of both child and adult sexual victimization. Overall, consistent with prior literature, developmental factors, individual traits, and alcohol expectancies predicted men’s and women’s sexual harassing and coercive behavior. Although there were many similarities across gender, important differences were also found primarily in the mediation process. Research has shown that even though sexual aggression is more frequently perpetrated by men, it is a ubiquitous social problem also committed by women. This study examined gender differences among 426 undergraduate students’ (148 males and 278 females at a large public university in the northeastern United States) use of sexually harassing and coercive behaviors. Tables, references