Background Screening for coronary artery calcium with electron beam computed tomography (EBCT) has potential diagnostic and prognostic implications. Most prior research on this technology has been done on selected, high-risk populations. The goal of the Prospective Army Coronary Calcium (PACC) study is to determine the utility of EBCT for the detection of coronary calcium as a screening test for coronary artery disease and as an intervention for risk factor modification among young, asymptomatic, active-duty personnel undergoing the United States Army’s Cardiovascular Screening Program. Methods and Results Three study designs will be used to address the objectives of this investigation: (1) a cross-sectional study of 2000 unselected, consecutive participants to determine the prevalence and extent of coronary calcification in the 40- to 45-year-old Army population, (2) a randomized, controlled trial with a 2 × 2 factorial design involving 1000 participants to assess the impact of EBCT information on several dimensions of patient behavior, with and without intensive risk factor case management, and (3) a prospective cohort study of 2000 participants followed for at least 5 years to establish the relation between coronary calcification and cardiovascular events in an unselected, “low-risk” (by conventional standards) Army population. Conclusions We present a review of the literature on the clinical utility of EBCT, with a focus on the limited research in young, asymptomatic populations. The details of the PACC study (begun in October1998) are presented. The results of the PACC study will determine the clinical utility of EBCT in young, asymptomatic patients. (Am Heart J 1999;137:932-41.)