Background: Decades of research indicate that physical activity is an important behavior for health promotion and disease prevention. Despite dissemination of these research findings, many American adults are sedentary. The rates for sedentary behavior vary by race/ethnicity and gender. Women and adults from minority groups are most likely to be sedentary. Research on adults who are physically active has identified several factors that predispose, enable, and reinforce this behavior. The presence of social support is one such factor. Purpose: The purpose of this study was to identify the nature and extent of social influence on physical activity in a nationally-representative sample of minority women. Methods: A telephone survey of 2912 women ages 40 and older from various racial/ethnic groups was conducted from July 1996 to June 1997. Information on physical activity as well as other preventive health behaviors was collected. Analysis: Descriptive analyses were done on physical activity levels (including an accumulation of household and occupational physical activity), physical activity-related social support (PASS), support network, and measures of social contact. Logistic regression was used to determine differences in PASS levels and physical activity. Linear Regression was used to determine the relationship between social influence and physical activity level. Results: Women with high levels of physical activity- related social support were more likely to meet recommended levels of physical activity. There was no difference by racial/ethnic group. An index of social influence was not a significant predictor or physical activity level among all women in the sample. Conclusion: While women with higher levels of specific support for physical activity were more likely to be physically active, a more general measure of social support did not predict level of physical activity. More research is needed in assessment of both physical activity and social support in this population.