In the current article, we address the existing assumption in the literature on cognitive behavioral treatment of PTSD that patients with severe negative trauma-related cognitions would benefit more from a treatment package that includes exposure and cognitive techniques compared with a treatment that includes exposure only. To test this assumption, 54 PTSD patients were randomized to prolonged exposure therapy or prolonged exposure therapy plus cognitive restructuring. Contrary to expectations, findings revealed that patients characterized by more severe pretreatment trauma-related cognitions (and more severe pretreatment PTSD symptoms) fared slightly worse in treatment combining exposure and cognitive restructuring. However, there was no relationship between pre- and post-treatment measures of negative cognitions and PTSD symptoms in the exposure alone group. The implications of these findings for examining Person X Treatment interactions and the efficacy of combining treatments for PTSD are discussed.