This article reviews issues relating to the prevalence, health implications, and prevention and treatment perspectives of obesity in U.S racial and ethnic minority groups. The growing interest in obesity in minority populations reflects an awareness of the high prevalence of obesity among black, Hispanic, Asian and Pacific Islander and Native Americans as well as a generally increased interest in minority health. In addition, the fact that some aspects of obesity among minorities differ from those in whites suggests that new insights may be gained from studying obesity in diverse populations. However, there are many methodological problems to be overcome, including some that arise from the way minority groups are defined. Under the assumption that all obesity results from a period of sustained positive energy balance at the individual level, an epidemiologic explanation for the excess of obesity in minorities at the population level seems readily apparent. A surplus of obesity-promoting forces and a deficit of obesity-inhibiting forces, caused by secular changes in food availability and physical activity, accompany the early phases of modernization and economic advancement. The high prevalence of obesity in minority populations can be viewed as a function of the slope and timing of these secular changes. Genetic predisposition, cultural attitudes, and exposure to maternal obesity and diabetes in utero may be potentiating factors. In this context, interventions targeting individuals would seem inevitably to put racial and ethnic minority groups on the path toward the same weight control crisis now observed in the majority white population. This suggests that the underlying causes of the societal energy balance problem must be addressed at the population level in order for effective clinical approaches to be developed for minority populations with a high obesity prevalence.