In the United States, injury is the leading cause of death for persons aged 1--44 years, and the approximately 800,000 emergency medical services (EMS) providers have a substantial impact on the care of injured persons and on public health. At an injury scene, EMS providers determine the severity of injury, initiate medical management, and identify the most appropriate facility to which to transport the patient through a process called "field triage." Although basic emergency services generally are consistent across hospital emergency departments (EDs), certain hospitals have additional expertise, resources, and equipment for treating severely injured patients. Such facilities, called "trauma centers," are classified from Level I (centers providing the highest level of trauma care) to Level IV (centers providing initial trauma care and transfer to a higher level of trauma care if necessary) depending on the scope of resources and services available. The risk for death of a severely injured person is 25% lower if the patient receives care at a Level I trauma center. However, not all patients require the services of a Level I trauma center; patients who are injured less severely might be served better by being transported to a closer ED capable of managing milder injuries. Transferring all injured patients to Level I trauma centers might overburden the centers, have a negative impact on patient outcomes, and decrease cost effectiveness. In 1986, the American College of Surgeons developed the Field Triage Decision Scheme (Decision Scheme), which serves as the basis for triage protocols for state and local EMS systems across the United States. The Decision Scheme is an algorithm that guides EMS providers through four decision steps (physiologic, anatomic, mechanism of injury, and special considerations) to determine the most appropriate destination facility within the local trauma care system. Since its initial publication in 1986, the Decision Scheme has been revised four times. In 2005, with support from the National Highway Traffic Safety Administration, CDC began facilitating revision of the Decision Scheme by hosting a series of meetings of the National Expert Panel on Field Triage, which includes injury-care providers, public health professionals, automotive industry representatives, and officials from federal agencies. The Panel reviewed relevant literature, presented its findings, and reached consensus on necessary revisions. The revised Decision Scheme was published in 2006. This report describes the process and rationale used by the Expert Panel to revise the Decision Scheme.