Veterans returning from the current conflicts in Iraq and Afghanistan exhibit high rates of comorbid mTBI/PTSD. Given the comorbidity and neuropsychiatric symptom overlap of these disorders, it can be difficult to determine whether problems and disruptions in functioning are due to mTBI, PTSD, or both. Hence, it is challenging for providers to know how to prioritize these patients' clinical issues and how to effectively treat them. Currently, there are no evidence-based treatments for comorbid mTBI/PTSD. Further, it is unclear to what extent existing treatments for each disorder can be adherently and effectively implemented for the other. As such, most current treatment recommendations suggest a holistic or integrated approach to treatment for comorbid mTBI/PTSD targeting symptoms and functionality rather than underlying etiology. We are proposing a treatment for comorbid mTBI and PTSD that directly targets daily functioning and quality of life. The primary objective of this study is to evaluate the efficacy of Cognitively Augmented Behavioral Activation (CABA), a new hybrid treatment for veterans diagnosed with comorbid mild Traumatic Brain Injury (mTBI) and posttraumatic stress disorder (PTSD). The study's specific goals are to determine whether: 1) CABA reduces PTSD symptoms in veterans with mTBI/PTSD, 2) CABA reduces cognitive-related functional impairment in veterans with mTBI/PTSD, 3) CABA results in improvements in depression symptoms, cognitive functioning, and quality of life in veterans with mTBI/PTSD; and 4) CABA is an acceptable treatment for veterans with mTBI/PTSD. The overall goal is to develop an evidence-based manualized treatment for comorbid mTBI/PTSD that can be readily implemented in Veterans Health Administration (VHA) treatment settings. The study design makes use of the convergent availability of resources at the two participating Veterans Administration Medical Centers (VAMCs) in Portland, Oregon, and Seattle, Washington to conduct a Randomized Controlled Trial (RCT) of CABA. The study will recruit a total of 192 OEF/OIF veterans, 96 participants at each site, enrolled at participating VAMCs who are diagnosed with both mTBI and PTSD. Inclusion criteria will be 1) OIF/OEF era Veterans enrolled at one of the participating VA sites who are able to provide informed consent, 2) Diagnosis of PTSD based on the Clinician Administered PTSD Scale (Blake et al., 1990), 3) Positive screen on the Structured Interview for Collecting Head Trauma Event Characteristics as outlined by the VA/DoD Clinical Practice Guideline for Management of Concussion/mTBI and positively endorsed any of the Neurobehavioral Symptom Inventory (NSI) cognitive symptoms items (items 13-17), 4) English speaking, able to travel to the primary care clinics weekly for 10 sessions and for the follow-up assessments, and willing to refrain from the initiation of additiona mental health treatment during the first 3 1/2 months of the active phase of treatment if they are assigned to the CABA condition, and 5) Willingness to participate in audio-recorded sessions. Exclusion criteria will be 1) Current substance dependence disorder with less than 30 days abstinence, 2) Current Bipolar or psychotic disorder, 3) Active suicidal intent indicating significant clinical risk, 4) Initiated psychotropic medication within 6 weeks prior to the first assessment; and 4) Auditory or visual impairments that would prevent ability to participate in the cognitive rehabilitation group or benefit from compensatory strategies. Eligible participants will be randomly assigned to either the CABA or Treatment as Usual (TAU) group. Participants in the CABA group will receive the CABA intervention during the first 14 weeks of their participation in the study, whereas TAU participants will continue to receive TAU (usual care in a PTSD specialty treatment clinic, but no CABA) during their participation in the study. Both groups will undergo evaluations at baseline, 7 weeks (mid-treatment), 14 weeks (post-treatment), and 39 weeks (6 month follow- up). During their study participation, all participants will continue to receive their usual medical care.