Background: Controlled qualitative methods complement quantitative treatment outcome research and enable a more thorough understanding of the effects of therapy and the suspected mechanisms of action. Aims: Thematic analyses were used to examine outcomes of cognitive processing therapy (CPT) for posttraumatic stress disorder (PTSD) in a randomized controlled trial of individuals diagnosed with military-related PTSD (n = 15). Method: After sessions 1 and 11, participants wrote “impact statements” describing their appraisals of their trauma and beliefs potentially impacted by traumatic events. Trained raters coded each of these statements using a thematic coding scheme. Results: An analysis of thematic coding revealed positive changes over the course of therapy in participants’ perspective on their trauma and their future, supporting the purported mechanisms of CPT. Conclusion: Implications of this research for theory and clinical practice are discussed.