To inform intervention development in a multisite randomized community trial, the Rapid Early Action for Coronary Treatment (REACT) project formative research was undertaken for the purpose of investigating the knowledge, beliefs, perceptions, and usual practice of health care professionals. A total of 24 key informant interviews of cardiologists and emergency physicians and 15 focus groups (91 participants) were conducted in five major geographic regions: Northeast, Northwest, Southeast, Southwest, and Midwest. Transcript analyses revealed that clinicians are somewhat unaware of the empirical evidence related to the problem of patient delay, are concerned about the practice constraints they face, and would benefit from concrete suggestions about how to improve patient education and encourage fast action. Findings provide guidance for selection of educational strategies and messages for health providers as well as patients and the public.