Theory and research suggest that posttraumatic stress disorder (PTSD) may mediate the relationship between child sexual abuse and adult sexual assault. However, little empirical research has examined the mediational role of PTSD. In the present study, the authors use structural equation modeling to examine the degree to which the three symptom clusters that define PTSD (reexperiencing, avoidance, and hyperarousal) contribute to sexual revictimization. To assess PTSD symptomatology, undergraduate women completed questionnaires (N = 1,449), which detailed the history and severity of childhood and adult sexual assault experiences. Results indicated that PTSD mediated sexual revictimization. When PTSD symptom clusters were examined individually, only the hyperarousal cluster was a significant mediator. Results are discussed in terms of information-processing mechanisms that may underlie sexual revictimization.