RecruitingPhase 2Behavioural interventionIntegration of Cognitive Processing Therapy and Relapse Prevention for Alcohol Use Disorder and PTSDThe goal of this clinical trial is to test the efficacy of a novel integrative cognitive-behavioral intervention in patients with posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD). Specific Aim 1: Examine the efficacy of CPT-RP, as compared to RP alone, in reducing alcohol frequency (percent days drinking) and quantity (drinks per drinking day) as measured by the Timeline Follow-Back (TLFB). Specific Aim 2: Examine the efficacy of CPT-RP, as compared to RP alone, in reducing PTSD symptoms as measured by the Clinician Administered PTSD Scale (CAPS-5). Specific Aim 3: Use ecological momentary assessment (EMA) to evaluate intervention effects on daily alcohol-related cognitions and behaviors through real-time associations with PTSD symptomatology and distress tolerance. Researchers will compare integrative CPT+RP with RP-alone to see if CPT+RP is more efficacious in reducing alcohol use and PTSD symptom severity.