OBJECTIVES To investigate family system outcome following acquired brain injury (ABI) using the Family Assessment Measure-III (FAM-III). RESEARCH DESIGN Clients and families referred to the Family Support Service completed the FAM-III, a measure of family system functioning. METHODS AND PROCEDURES Forty-three persons and 92 family members completed the FAM-III as part of intake. FAM-III scores were calculated and compared within the family, between subscales, and with established norms. RESULTS FAM-III scores of the family member sample were significantly elevated compared to individuals with ABI and compared to the norm across all seven domains of family functioning. No significant relationship was found between family member relationship status or time post-injury and overall FAM-III scores. CONCLUSIONS Family members identified distressed family functioning across all domains compared to survivors and compared to population norms. The FAM-III provides clinical utility in assessing family system functioning and shows promise as a family system outcome measure.