The purpose of this study was to describe the relationship among variables which are associated with life-style modification, knowledge of diabetes, social support, health practices, and body mass index, to examine their effect on health status, and to test the effectiveness of a community based life-style modification program for weight control. Adults (n = 66) with non-insulin-dependent diabetes mellitus participated in either a treatment or control group. The treatment consisted of 5 weekly 90-min sessions on modifying eating and exercise patterns. All participants completed a personal resource questionnaire (PRQ), health practices survey (HPS), and diabetes health status questionnaire (DHS) at intake, 5 weeks, and 4 months. Knowledge of diabetes was assessed only at intake. Knowledge of diabetes, social support, and health practices explained 27% of the variance in health status, but health practices explained the largest (18%) proportion of the variance and was the only study variable significantly affected by the life-style modification program.