The relationship of social networks and social support to the psychosocial functioning (self-efficacy, self-esteem, anxiety, depression, and hostility) of 159 American Indian women undergoing residential substance abuse treatment at Native American Connections was assessed. Social support and active participation by clients' families during treatment were found to be significantly related to improved psychosocial functioning. No relationship was found between positive social networks and psychosocial improvement. Interventions for substance abuse should aim to include family and friends in clients' treatment. (Contains 5 tables and 1 figure.)