Rape is believed to be one of the most underreported crimes with 3 to 10 rapes committed for every one that is reported. Rape represents an extreme behavior which can be placed on a continuum of sexual aggression defined by degrees of coercion and force. The prevalence of sexual aggression among college students nationally was examined in 3,187 female and 2,872 male college students enrolled in 32 colleges chosen for their national diversity. A self-reporting questionnaire was administered in classes which included questions on demographics, sexual experiences before and after age 14, family and social history, current behavior, and psychological characteristics. The results indicated that 15.4 percent of college women reported experiencing legal rape and 4.4 percent of college men reported perpetrating legal rape. An additional 12.1 percent of women reported having experienced attempted rape and 3.3 percent of men reported having attempted to rape someone. Virtually none of these crimes were reported and thus represent "hidden rape" not reflected in crime statistics. Men did not admit to the levels of sexual aggression that women reported. Few women reported the crime or sought victim assistance. Rates of sexual victimizaton/aggression were robust and did not vary with school size, type of institution, location, or population size. Future research should investigate conditions which lead to this violence. (ABL)