BACKGROUND A new diagnosis, complex posttraumatic stress disorder (CPTSD), is set to be introduced in the 11th revision to the International Classification of Diseases (ICD-11). Studies have supported a unique group of trauma-exposed individuals who exhibit symptoms consistent with CPTSD proposals. No studies have yet tested the proposed latent symptom structure of CPTSD proposed for ICD-11. This study tests the factorial validity of CPTSD and assesses the role of a range of risk factors to predict CPTSD. METHOD A large sample (N = 453) of treatment-seeking adult victims of childhood sexual abuse completed self-report measures of CPTSD. Confirmatory factor analysis (CFA) was used to compare a set of alternative factor models of CPTSD. RESULTS Just less than half of the sample met the diagnostic criteria for CPTSD (42.8%). CFA results supported the factorial validity of the ICD-11 proposals for CPTSD. Being female and experiencing a greater number of sexual abuse acts during childhood were more strongly associated with PTSD than CPTSD symptoms. Regarding symptoms, anxiety was more strongly associated with PTSD than CPTSD, whereas higher levels of dysthymia were more strongly associated with CPTSD than PTSD symptoms. CONCLUSIONS Results provide initial evidence regarding the factorial validity of the proposed ICD-11 model of CPTSD. In addition, current results support the proposals of the ICD-11 that exposure to abuse during early development is associated with a greater likelihood of CPTSD than PTSD. The study contributes to a growing body of empirical data supporting the construct validity of CPTSD as a unique diagnostic entity. (PsycINFO Database Record