In 1960, the original Evans County Study cohort was formed when 92 percent of all residents, Black and white, aged 40-74 years and a 50 percent sample of residents aged 15-39 years were given a complete physical examination and a variety of laboratory tests. The major purpose of the original study was to determine factors associated with coronary and related cardiovascular diseases and to explain the low frequency of coronary heart disease in Blacks. Of the initial cohort of 3,102 individuals in 1960, approximately 2,500 were re-examined from 1967 to 1969. Variables studied included serum lipid levels, blood pressure, blood clotting factors, catecholamine levels, physical activity, and social, psychological, and economic factors. Necropsy data were also collected. Follow-up continued on the remaining cohort of approximately 1,900.