Social isolation is a prevalent and highly prioritized concern among people with traumatic brain injury (TBI), contributing to poor physical and mental health outcomes. Existing rehabilitation interventions have focused primarily on remediating underlying impairments, with limited success in improving social participation. A patient-directed, self-management approach may offer a promising alternative. This study aims to evaluate the feasibility of ENGAGE-TBI, a novel, theory-driven occupational therapy intervention designed to reduce social isolation by increasing social participation among community-dwelling adults with TBI. Using a single-group pre-post design, this study will enroll 30 adults with TBI recruited through the Brain Injury Association of Missouri. ENGAGE-TBI is a 12-session group intervention co-facilitated by an occupational therapist and a peer mentor with TBI. The intervention integrates three core elements - social learning, guided problem-solving, and skilled community practice - delivered across six weeks. Feasibility outcomes include fidelity, participant engagement, satisfaction, attendance, and retention. The primary clinical outcome is social participation, measured using the PROMIS Ability to Participate in Social Roles and Activities. Feasibility outcomes will be examined descriptively against pre-specified benchmarks. Within-group Cohen's d effect sizes with 95% confidence intervals will be calculated to estimate intervention effects and variability, informing the design of a future randomized controlled trial. Findings will support the development of a fully-powered effectiveness trial. This study addresses a critical gap in TBI rehabilitation by testing a stakeholder-informed, community-based intervention that treats TBI as a chronic condition and prioritizes patient-directed goal achievement over impairment remediation.