Both epidemiologic and clinical research in coronary heart disease have increased our awareness that some risk factors for disease such as obesity, hypertension, and hypercholesterolemia may be partially determined by genetic factors or habits which are formed in infancy, childhood, and adolescence. Studies to date also suggest that some of the coronary heart disease risk factors do not change dramatically before the late teenage years and that differences in characteristics by sex or race are most pronounced after this time. However, relatively little work has been done to identify the characteristics of young adult life which may be precursors to or coincident with the increase in risk factors prior to middle age. While major increases in certain risk factors occur in young adulthood in conjunction with significant changes in life style, the interrelationships among these risk factors and changes have not been rigorously investigated.