This study investigates the contribution of pre-injury family functioning and resources on self-reported post-concussive symptoms and functional outcomes in persons with mild TBI (mTBI). Participants with uncomplicated or complicated mTBIs were recruited from consecutive admissions to the emergency department of a level 1 trauma centre. Patients completed baseline assessments within 2 weeks of injury and an outcomes assessment at 3 months post-injury. One hundred and sixty-six adults with mTBI were included. Baseline measures of pre-injury history, family functioning and resources were obtained. Functional status assessments and self-reported measures of health, common TBI symptoms and psychological problems were administered at 3-months post-injury. Data reduction of outcome measures using principle components analysis revealed two factors: self-reported post-concussive symptoms and current functional/participation status, explaining 60.53% of the variance. Family resources (β = –0.239, t(150) = –2.84, p = 0.005) and age (β = –0.170, t(150) = –2.19, p = 0.030), but not family functioning, were significant predictors of self-reported post-concussive symptoms at follow-up, R² = 0.051, F(5, 150) = 4.09, p = 0.002. Neither family resources nor functioning predicted current functional/participation status. Fewer family resources and younger age were associated with increased self-reported post-concussive symptoms. Fewer resources may be a potential risk factor to heightened perception of post-concussive symptoms. Providing low-cost counselling or resource facilitation services may improve outcomes for those with limited resources after mTBI.