This study examined factors associated with PTSD-depression comorbidity among a sample of 162 adult female rape or assault victims with PTSD, as well as potential differential predictors of PTSD and depression severity. PTSD-only participants reported higher levels of childhood sexual abuse than those with comorbid PTSD and depression, and the PTSD/MDD group reported relatively more distorted trauma-related beliefs, dissociation, PTSD severity, and depression severity. Distorted trauma-related beliefs and dissociation were the strongest unique predictors of higher PTSD and depressive symptoms. Rates of PTSD and depression comorbidity did not appear to be a function of symptom overlap. Study findings suggest possible explanations for the high PTSD and depression comorbidity rates commonly found among victims of interpersonal violence.