Participants were recruited from the Field Centers and screened for evidence of subclinical coronary atherosclerosis, using electron-beam computed tomography (EBCT) or another noninvasive measure of subclinical disease, and for coronary risk factors. A sample of those at highest risk for coronary heart disease events, within defined age-, sex- and ethnicity-strata and an age-, sex-, ethnicity-, center-matched sample of participants representing the normal spectrum of subclinical coronary disease were reexamined in more depth approximately six months later for other evidence of subclinical disease and for characterization of possible precursors of disease events. The cohort was characterized with respect to coronary calcification (using computed tomographic scanning), ventricular mass and function (using cardiac magnetic resonance imaging), flow-mediated endothelial function, carotid intimal-medial wall thickness and distensibility in the carotid artery (using ultrasonography), lower extremity vascular insufficiency (using ankle-brachial blood pressure indices), electrocardiographic measures, standard coronary risk factors, sociodemographic factors, lifestyle factors, and psychosocial factors. Blood samples were assayed for putative biochemical risk factors and stored for case-control studies. DNA was extracted and lymphocytes immortalized for study of candidate genes and possibly genome-wide scanning. Four clinical examinations, 18 to 24 months apart, were planned. Exam 2, beginning in September 2002 and ending in January 2004, included repeat coronary calcification measures and carotid MRI in subsets of the cohort. Exam 3 is underway. A second cardiac computed tomography is performed on the cohort during Exams 2 and 3.