The lifetime prevalence of traumatic events and their psychological impact were assessed in 440 undergraduate students. Eighty-four percent of the subjects reported experiencing at least one event of sufficient intensity potentially to elicit Post- Traumatic Stress Disorder (PTSD). One-third of the sample had experienced four or more traumatic events. Subjects who had experienced trauma reported higher levels of depression, anxiety, and PTSD symptomatology than nontraumatized subjects, and these symptoms were more intense in subjects who experienced multiple traumas. Events that were particularly negative in their impact included unwanted sexual experiences and events that subjects reported were too traumatic to discuss openly. Males and females differed in their probability of experiencing some types of events and in the psychological response to certain events.