The study draws on the success of the Los Angeles South Bay Heart Watch (SBHW) in recruiting an ethnically-diverse sample of individuals at high risk of coronary heart disease events who have undergone serial evaluation by both assessment of conventional coronary heart disease risk factors and by evaluation of coronary arterial calcification by fluoroscopy and by EBCT on sequential evaluations. The study group has been able to maintain contact with the participants and achieve outstanding rates of both contact for follow-up and repeat participation in sequential components of the study.