This study investigated the degree of association between four sets of predictor variables (demographic, injury-related, patient functioning, and caregiver functioning variables) and the criterion variable of long-term family functioning following severe traumatic brain injury (TBI). Thirty families participated in the study and a minimum of 3.5 years had elapsed since the time of injury. The mean length of post-traumatic amnesia (PTA) for the brain-injured individuals was 92.4 days. Data collection took place in the family home and both the brain-injured family members and primary caregivers were involved. Standard regression analyses revealed that two sets of variables accounted for a significant amount of variance in long-term family functioning. The largest amount of variance, 55% (44% adjusted), was accounted for by the caregivers' self-report variables which measured caregivers' depression, social support, and coping as well as caregivers' preceptions of patient competency. Overall, measures of severity of injury (PTA), residual neurobehavioural function, and adequacy of social support for caregivers proved to be reliable and significant indicators of family functioning. These findings are discussed with respect to their implications for service delivery and long-term provision of support for caregivers of severely brain-injured individuals living with their families.