ObjectiveTo examine risk factors associated with homeboundness 1-year following traumatic brain injury (TBI) and to explore associations between homebound status and risk of future mortality and nursing home entry. DesignSecondary analysis of a longitudinal prospective cohort study SettingTBI Model Systems (TBIMS) Centers ParticipantsCommunity-dwelling TBIMS participants (n=6,595) who sustained moderate-severe TBI between 2006-2016, and resided in a private residence 1-year post-injury. InterventionsN/A Main Outcome MeasuresHomebound status (leaving home ≤1-2 days per week), 5-year mortality, and 2- or 5-year nursing home entry. ResultsIn our sample, 14.2% of individuals were homebound 1-year post-injury, including 2% who never left home. Older age, having less than a Bachelor's degree, Medicaid insurance, living in the Northeast or Midwest, dependence on others or special services for transportation, unemployment or retirement, and needing assistance for locomotion, bladder management, and social interactions at 1-year post-injury were associated with being homebound. After adjustment for potential confounders and an inverse probability weight for nonrandom attrition bias, being homebound was associated with a 1.69-times (95% CI: 1.35-2.11) greater risk of five-year mortality, and a non-significant but trending association with nursing home entry by 5 years post-injury (RR=1.90, 95% CI: 0.94, 3.87). Negative associations between homeboundness and mortality were consistent by age subgroup (± 65 years). ConclusionsThe negative long-term health outcomes among persons with TBI who rarely leave home warrants the need to re-evaluate home discharge as unequivocally positive. The identified risk factors for homebound status, and its associated negative long-term outcomes, should be considered when preparing patients and their families for discharge from acute and post-acute rehabilitation care settings. Addressing modifiable risk factors for homeboundness, such as accessible public transportation options and home care to address mobility, could be targets for individual referrals and policy intervention.