In the general population, women's lifetime risk of developing posttraumatic stress disorder (PTSD) is twice that of men's. However, evidence is contradictory as to whether this sex difference is present among child abuse/neglect victims. The authors examined sex differences in PTSD among a sample of 674 individuals with documented child abuse/neglect histories assessed for PTSD in adulthood. Across all types of abuse/neglect, women were more than twice as likely to develop PTSD as men. The sex difference was greatest among sexual abuse victims. Female victims' greater revictimization explained a substantial proportion (39%) of the sex differences in PTSD risk. Future research should identify mechanisms that make female victims particularly vulnerable to revictimization and the development of PTSD.