The data came from a Canadian national representative sample survey of 1,835 female and 1,307 male college and university students on 38 campuses. The analysis used data from the 95.5 percent of the women and 94.8 percent of the men who said that they had ever dated a member of the opposite sex. The study measured the incidence of sexual assault, drinking of alcohol, drinking with their dating partners, recreational drug use, and male peer support for the males who sexually assaulted women. Results supported routine activities theory and revealed that men who drank 2 or more times a week and had male peers who supported both emotional violence and physical violence were nearly 10 times as likely as men without any of these traits to admit to being sexual aggressors. Findings suggested that motivated male offenders regarded women who drank, consumed drugs, or both as suitable targets and that these attitudes were largely a function of ties and social exchanges with male peers who perpetuated and legitimated sexual assault in college dating relationships, in combination with the use of alcohol by the men themselves. The analysis indicated the need for prevention and control strategies targeting the broader social, social psychological, and psychological factors that motivate men to abuse female intimates and strangers sexually and that efforts based solely on self-defense and awareness campaigns for women were insufficient. Tables, footnotes, and 54 references (Author abstract modified)