Although not all scientists agree that obesity is an independent risk factor for coronary heart disease, it may be a strong univariate predictor of coronary heart disease, and impacts on coronary heart disease through at least some of its relationships with other risk factors: positive association with blood pressure, inverse association with high density lipoprotein cholesterol (HDLC), positive association with triglyceride and very low density lipoprotein cholesterol (VLDLC), and a positive association with hyperglycemia and diabetes. A number of these have been shown to be major coronary heart disease risk factors. Prevention of obesity, or weight reduction towards desirable body weight may reduce the incidence of coronary heart disease and some of its risk factors. There is evidence to suggest that once obesity begins and/or advances in childhood, it will track into adulthood, with a reasonably high level of certainty. Obesity becomes progressively more difficult to treat with maturation to adulthood. Thus, better understanding of the pathophysiology of obesity in late childhood and early adolescence should, in the long-run, provide the basis for effective prevention or intervention programs in order to have a long-range impact upon the consequence of obesity. The age group 9 and 10 at entry has been selected to assure that many of the individuals are enrolled prior to puberty, and followed through this transition period when obesity becomes more apparent among Black adolescent females than among white.