This is the first study of unwanted sexual experiences in the collegiate "hooking-up" culture. In a representative sample of 178 students at a small liberal arts university. Twenty-three percent of women and 7% of men surveyed reported one or more experiences of unwanted sexual intercourse. Seventy-eight percent of unwanted vaginal, anal, and oral incidents took place while--"hooking up,"-- whereas 78% of unwanted fondling incidents occurred at parties or bars. The most frequently endorsed reason for unwanted sexual intercourse was impaired judgment due to alcohol. The most frequently endorsed reason for unwanted fondling was that it happened before the perpetrator could be stopped. Of those affected by unwanted sexual intercourse or unwanted fondling, 46.7% and 19.2% reported unwanted memories, 50% and 32.7% reported avoidance and numbing responses, and 30% and 26.9% reported hyperarousal responses, respectively. A preliminary model of unwanted sex and collegiate social dynamics is proposed to provide a heuristic for further research. (Contains 2 tables and 1 endnote.)