The work group in charge of editing the trauma disorders in the upcoming edition of the International Classification of Diseases (ICD-11) made several changes to the trauma criteria. Specifically, they simplified the criteria for posttraumatic stress disorder (PTSD) and added a new trauma disorder called complex PTSD (CPTSD). To assess the new and newly defined trauma disorders, Litvin, Kaminski and Riggs developed a self-report trauma measure called the Complex Trauma Inventory (CTI). Although the reliability and validity of the CTI has been supported, no empirically-derived cutoff scores exist. We determined the optimal CTI cutoff scores using receiver operating characteristic (ROC) analyses in a diverse sample of 82 participants who experienced trauma and were recruited from an inpatient trauma unit, student veteran organizations, and university classrooms. We used the Clinician-Administered Interview for Trauma Disorders (CAIT) to diagnose the presence of an ICD-11 trauma disorder, and we correlated the results of the CAIT with the Clinician-Administered PTSD Scale for the DSM-5 to establish the convergent validity of the CAIT, r = .945, p < .001. For the ROC analyses, the CTI was used as the index test and the CAIT was used as the criterion test. The area under the curve (AUC) …