The hospital records of every 1996 cardiac discharge from each of three Baltimore-area hospitals are reviewed to assign each patient to one of three classes. These classes reflect the medical appropriateness of coronary angiography as estimated by the American College of Cardiology and the American Heart Association. All patients in class 1 (indicating general agreement that coronary angiography is indicated) are interviewed by telephone to ascertain barriers to utilization and other factors that may contribute to the use of services. In addition, a stratified sample of 16 class 1 subjects are interviewed in depth. An estimated 400 referring physicians are surveyed to develop a typology of physician practice patterns. Results from patient surveys, physician surveys, and medical record reviews are merged to form the analytical database.