Nearly 400,000 Veterans have been diagnosed with traumatic brain injury (TBI) since 2000, representing up to 22% of combat casualties. Depression is one of the most prevalent and serious of TBI sequelae. Post- TBI depression adversely affects rehabilitation, treatment adherence, community reintegration (CR), quality of life (QOL), social relationships, and caregiver burden. Yet, post-TBI depression remains under-assessed, undertreated, and under-studied. No clinical guidelines for post-TBI depression treatment exist, and current treatment is largely based on expert opinion rather than evidence from controlled clinical trials. A promising therapeutic approach to post-TBI depression is Behavioral Activation (BA), a brief and pragmatic treatment rigorously tested since the 1970s in clinical trials for depression in diverse clinical populations. BA can accommodate hallmark deficits of TBI such as deficits in memory, organization, planning, initiation, emotion regulation, and interpersonal functioning. It can be delivered by professionals routinely available in VA outpatient rehabilitation services (e.g., occupational therapists, nurses, psychologists, social workers) and, therefore, can be deployed in rehabilitation settings. The proposed research will assess the feasibility of a BA protocol adapted for post-TBI depression in an outpatient VA rehabilitation setting. Specific study objectives are to: (1) assess BA's acceptability to veterans and staff and other feasibility indices, (2) provide preliminary evidence of participant response in the outcomes of depressive symptoms, CR, and QOL at the 3-month follow-up interview, (3) develop the BA protocol and manual to be tested in a larger randomized controlled trial (RCT) in the future, and (4) explore engagement in activity as the mechanism that underlies BA intervention effects on outcomes. This feasibility study will enroll 40 male and female veterans receiving care at a VAMC Rehabilitation Medicine Service and meeting study criteria for TBI and depression. Veterans will be randomly assigned to BA plus treatment as usual (TAU) or control (TAU). The BA program consists of six sessions delivered over 3 months at the VA (or veterans' homes, if preferred) by an occupational therapist (OT). All veterans are interviewed at baseline before randomization and 3 months later by a blinded interviewer. Both interviews assess veterans' depressive symptoms, CR, and QOL, using standardized instruments. Feasibility will be evaluated in terms of acceptability to veterans and clinic staff, process variables (e.g., retention, study completion rates), safety, adequacy of eligibility criteria, participant comprehension, and research burden, using a priori criteria for success. Finally, phone interviews with BA participants and staff will be conducted to capture their experience with BA. These qualitative and quantitative methods are designed to test the feasibility of a future RCT, to identify the barri...