This study examined the impact of four domains upon the quality of life (QOL) of senior residents living in assisted living homes: (a) demographic characteristics and health status, (b) social involvement, (c) facility characteristics, and (d) the social climate. Participants were 201 residents with functional impairments living in 55 different assisted living facilities in California. QOL was measured with three scales of depression, life satisfaction, and facility satisfaction. Bivariate correlations and ANOVAs found significant relations between at least one of the QOL measures and age, health status, social and family involvement measures, facility characteristics, and social climate measures. Social climate measures of cohesion, conflict, and independence had the strongest zero-order correlations. Regression analyses for the three QOL measures found cohesion to be the strongest predictor in all three regressions. Other QOL predictors in the regression analyses were fewer health conditions, participation in social activities, monthly family contact, and an environment low in conflict. Findings suggest that assisted living homes can improve resident QOL by creating a cohesive social environment, and encouraging social participation and family involvement.