ARIC is a large-scale, long-term program that measures associations of established and suspected CHD risk factors with both atherosclerosis and new CHD events in men and women from four diverse communities. The project has two components: community surveillance of morbidity and mortality, and repeated examinations of a representative cohort of men and women in each community. The representative cohorts include 4,000 persons from each community. Three of these reflect the ethnic composition of the communities in which they live; one cohort is black. The community surveillance involves abstracting hospital records and death certificates and investigating out-of-hospital deaths for hospitalized myocardial infarction and CHD death in 800,000 men and women in these four communities.