The main hypothesis being tested is that a cognitive behavioral therapy (CBT) for posttraumatic stress disorder (PTSD) can improve treatment retention and outcomes for both posttraumatic stress and substance use disorders. The investigators have completed a Safety & Practicality Study and a Feasibility Study and both studies found that CBT for PTSD was safe and effective in reducing PTSD symptoms, improving retention, and in reducing substance use. The present study proposes to continue testing the hypotheses by evaluating and comparing the PTSD, retention and substance use outcomes resulting from CBT versus a control condition. This is termed the "Pilot Trial" phase of behavioral therapy development and requires comparing the investigational treatment (CBT) with a control treatment, within the context of addiction treatment-as-usual (intensive outpatient programs or methadone maintenance clinic settings). The results of this study will then be used to develop a RO1 grant application to NIDA to support a Stage II efficacy study (randomized controlled trial).