This study examines the mechanisms by which family-supportive supervision is related to employee work-family balance. Based on a sample of 170 business professionals, we found that the positive relation between family-supportive supervision and balance was fully mediated by work interference with family (WIF) and partially mediated by family interference with work (FIW) such that having a supportive supervisor was associated with low WIF and FIW which, in turn, were related to high balance. Consistent with an enhancement perspective, the relation between family-supportive supervision and balance was stronger for employees in family-supportive organizational environments than unsupportive environments and was stronger for employees with supportive spouses than unsupportive spouses. We discuss the theoretical implications of the findings and suggest areas for additional research. (Contains 2 figures and 5 tables.)