PREPAREDNESS AND ORGANIZATION of a healthcare facility are required to maximize the utilization of the available resources to provide the highest achievable level of care for the community during a disaster. This requires the development of an Emergency Management Program (EMP) aimed at: (1) protecting the facility and its people (patients and staff); (2) responding to the community's increased healthcare needs; (3) continuing to provide healthcare services; and (4) assuring the safety of all involved. In contrast to a hospital's usual way of functioning and managing healthcare utilizing consensus decision-making based on extensive data, responding to a large-scale crisis requires that time-sensitive decisions be made with imperfect information. Controlling the situation not only requires planning, it requires the delineation of alternate roles and responsibilities of hospital staff in an organized management system. Central to this organization is a command structure that details the roles and responsibilities of those involved in leading the healthcare facility through all phases of a disaster. In the United States, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) requires that hospitals establish a hospital Incident Command System (ICS). Beginning in 2006, the US Department of Health and Human Services outlined in its Hospital Preparedness Program similar expectations in an effort to promote hospital compliance with National Incident Management System (NIMS) principles, including the use of an ICS that is consistent with that found within the facility's community.