The objective of this study was to identify the risk factors associated with the dissociative symptomatology of borderline patients. The Dissociative Experiences Scale-a 28-item self-report measure that has well documented reliability and validity-was administered to 290 criteria-defined borderline patients and 72 axis II comparison subjects. Semistructured interviews pertaining to difficult childhood experiences and adult experiences of being a victim of violence were administered to these patients blind to diagnostic status. In the sample of borderline patients alone, multiple regression analyses revealed that four risk factors were found to be significantly associated with the level of dissociation reported by these 290 patients: inconsistent treatment by a caretaker, sexual abuse by a caretaker, witnessing sexual violence as a child, and adult rape history. In the combined sample of axis II patients, the borderline diagnosis joined these four "traumatic" factors as a significant predictor of the overall level of dissociation reported by these 362 personality-disordered inpatients. The results of this study suggest that both sexual trauma and something intrinsic to the borderline diagnosis itself are risk factors for dissociative phenomena among borderline patients.