The U.S. Department of Health and Human Services’ Metropolitan Medical Response (MMRS) program has evolved from an idea originally developed in the Washington, D.C., area in 1995. Using the combined personnel and equipment resources from Washington, D.C., Arlington County in Virginia, and Montgomery and Prince Georges Counties in Maryland, the Metropolitan Medical Strike Team (MMST) received training, equipment, and supplies specifically designed to facilitate an effective response to a mass-casualty terrorism incident with a weapon of mass destruction (WMD). The first of its kind in the civilian environment, the MMST was intended to be capable of providing initial, on-site emergency health, medical, and mental health services after a terrorist incident involving chemical, biological, or radiological (CBR) materials. The team’s mission includes CBR agent detection and identification, patient decontamination, triage and medical treatment, emergency transportation of patients to local hospitals, coordination of movement of patients to more distant hospitals via the National Disaster Medical System (NDMS), and planning for the disposition of nonsurvivors. Building from the initial efforts of the Washington, D.C., Metropolitan Area MMST, OEP provided funding for the development of a similar team in the city of Atlanta in preparation for the 1996 Summer Olympic Games. The U.S. Congress has subsequently authorized and provided funding for additional contracts with the 120 most populous U.S. cities.Tools for Evaluating the Metropolitan Medical REsponse System Program: Phase I Report identifies and develops performance measures and systems to assess the effectiveness of, and to identify barriers related to, the MMRS development process. This report identifies, recommends, and develops performance measures and systems to assess the effectiveness of, and identify barriers related to, the MMRS development process at the site, jurisdictional, and governmental levels.