This article outlines theoretical considerations for diet and weight control of non-insulin-dependent diabetes mellitus (NIDDM) and identifies factors that may be of particular importance in influencing the success of diet and weight control of NIDDM in the Black population. Long-term adherence to dietary or weight-control regimens requires that the patient evaluate and restructure established eating and physical activity patterns. With the use of the social action theory as a conceptual framework, this complex behavioral change task can be understood as a function of the interplay of various self-regulatory mechanisms. These mechanisms are influenced by the person's capabilities for making changes, his/her physical condition and general health status, the physical and social environmental context, and the person's material and social resources. Many of these factors may differ for Blacks and Whites in a direction that suggests a lesser potential for effective diet and weight-loss therapy among Black NIDDM patients. For example, compared with Whites, Blacks are more likely to have limited incomes, low educational attainment, ambivalence about weight control, multiple health problems, and high-fat high-sodium low-fiber diets or food preferences. However, some evidence suggests that state-of-the-art counseling approaches can be as effective for Blacks as for Whites. The challenge is to adapt the types of approaches suggested by the social action theory for culturally appropriate and cost-effective delivery in Black community health-care settings.