This study aims to increase our understanding of trauma positive outcomes by (a) exploring associations between posttraumatic growth and posttraumatic stress disorder (PTSD), and (b) investigating posttraumatic growth course and its impact on exposure treatment. In 80 mixed trauma PTSD patients, growth was negatively related to PTSD symptoms, especially emotional numbing. Sixty-five PTSD patients also completed Prolonged Exposure therapy with pretreatment and posttreatment assessments. Posttraumatic growth—New Possibilities and Personal Strength—increased during exposure therapy, and these increases were associated to decreases of PTSD symptoms. Pretreatment posttraumatic growth, more specifically the Appreciation of Life subscale, predicted better treatment outcome after controlling for pretreatment PTSD. The results indicate that posttraumatic growth may be a valuable new concept in trauma therapy.