We evaluated behavioral programs designed to enhance the management of Non-Insulin Dependent Diabetes Mellitus (NIDDM). Although physicians routinely advice patients to make dietary and exercise changes, few systematic studies have evaluated the impact of this advice upon health status. In particular, few studies have considered adherence to behavioral programs and reports of follow-up are rare. Thirty-two men and forty-four women were randomly assigned to one of the four conditions: diet, exercise, diet plus exercise, or education control. Eachtreatment lasted ten weeks. Patients were assessed prior to the interventions, at three months, and at six months. The measures included blood glucose, glycosylated hemoglobins, lipid profiles, and body composition. Patients assigned to the diet group experienced significantly greater reductions in weight and blood glucose and significant increases in HDL cholesterol in comparison to other groups. Physical conditioning was not associated with changes in physiological measures. Across groups, there were significant correlations between adherence and outcome.