Abstract: Cognitive Processing Therapy (CPT) is an evidence-based treatment for posttraumatic stress disorder (PTSD) that is effective for many, but not all, people. The present study investigated a possible interaction of sex and trauma type to predict variable responses to treatment. Veterans from an outpatient Veterans Health Administration clinic completed the PTSD Checklist before CPT initiation and after treatment completion. Veterans' index traumatic events were coded by PTSD specialists as military operations-related or nonmilitary operations-related traumas. The final symptom levels were compared to the pre-assessment, determining treatment success and symptom-point reduction. Comparisons with regression models were calculated, testing sex and trauma types as predictors of PTSD symptom reduction at the end of treatment. Sex was a small but significant independent predictor of final PTSD symptom severity, such that women reported lower PTSD symptom scores than men by the end of CPT (B=-14.42, p=.001, η(2)=.032). Neither the direct effect of trauma type (B=3.13, p=.122) or the interaction of sex and trauma type were significant (B=8.85, p=.081). These findings add to a growing body of literature that male Veterans do not benefit as much from CPT as female Veterans and suggest the difference is not driven by trauma type. Clinical implications are presented.