Context: Delayed access to medical care in patients with acute myocardial infarction (AMI) is common and increases myocardial damage and mortality. Objective: To evaluate a community intervention to reduce patient delay from symptom onset to hospital presentation and increase emergency medical service (EMS) use. Design and Setting: The Rapid Early Action for Coronary Treatment Trial, a randomized trial conducted from 1995 to 1997 in 20 US cities (10 matched pairs; population range, 55777-238912) in 10 states. Participants: A total of 59944 adults aged 30 years or older presenting to hospital emergency departments (EDs) with chest pain, of whom 20364 met the primary population criteria of suspected acute coronary heart disease on admission and were discharged with a coronary heart disease-related diagnosis. Intervention: One city in each pair was randomly assigned to an 18-month intervention that targeted mass media, community organizations, and professional, public, and patient education to increase appropriate patient actions for AMI symptoms (primary population, n = 10563). The other city in each pair was randomly assigned to reference status (primary population, n = 9801). Main Outcome Measures: Time from symptom onset to ED arrival and EMS use, compared between intervention and reference city pairs. Results: General population surveys provided evidence of increased public awareness and knowledge of program messages. Patient delay from symptom onset to hospital arrival at baseline (median, 140 minutes) was identical in the intervention and reference communities. Delay time decreased in intervention communities by -4.7% per year (95% confidence interval [CI], -8.6% to -0.6%), but the change did not differ significantly from that observed in reference communities (-6.8% per year; 95% CI, -14.5% to 1.6%; P = .54). EMS use by the primary study population increased significantly in intervention communities compared with reference communities, with a net effect of 20% (95% CI, 7%- 34%; P<.005). Total numbers of ED presentations for chest pain and patients with chest pain discharged from the ED, as well as EMS use among patients with chest pain released from the ED, did not change significantly. Conclusions: In this study, despite an 18-month intervention, time from symptom onset to hospital arrival for patients with chest pain did not change differentially between groups, although increased appropriate EMS use occurred in intervention communities. New strategies are needed if delay time from symptom onset to hospital presentation is to be decreased further in patients with suspected AMI.