Objective: Although prolonged exposure therapy (PE) has been shown to be effective in treating posttraumatic stress disorder (PTSD), a sizable minority do not benefit. Examining patient and therapist characteristics that impact treatment outcome may improve treatment delivery and identify individuals who are less likely to respond to treatment or are at risk to prematurely discontinue treatment. The current study uses a sample from a large urban Veterans’ Affairs (VA) hospital to build on a previous report that identified correlates of treatment outcome for Veterans who received PE. Method: Two hundred eighty-seven veterans completed measures of PTSD, depression, and quality of life at the beginning and end of treatment. Veterans’ service-connected disability rating, therapist experience, benzodiazepine prescription, and traumatic brain injury diagnosis were investigated as predictors of treatment outcome in linear regression analyses. Results: Results showed that Veterans with a service-connected disability for a mental health condition had smaller treatment gains than those without service connection (p < .01). Additionally, results showed that patients treated by certified PE therapists had larger treatment gains than those treated by noncertified PE therapists (p < .01). Finally, younger age and therapist certification were associated with dropout from treatment (p < .05). Conclusion: Veterans treated by PE-certified therapists and Veterans who were not service-connected for a mental health condition fared better in treatment. Results suggest that additional study of both the national effort to train VA clinicians in PE and the impact of service connection on PTSD treatment outcome may be helpful for future research.