In the aftermath of the terrorist attacks of September 11, 2001, and the anthrax attacks in the fall of 2001, federal and state personnel carried out their mission to provide response, recovery, and remediation under trying circumstances, including an unprecedented demand on their capabilities to analyze environmental samples. In reviewing these events, EPA identified several areas where the country could better prepare itself in the event of future terrorist incidents. One of the most important areas identified was the need to improve the nations laboratory capacity and capability to analyze environmental samples following a homeland security event. In response, EPA formed the Homeland Security Laboratory Capacity Workgroup to identify and implement opportunities for near-term improvements and to develop recommendations for addressing longer-term laboratory issues. The EPA Homeland Security Laboratory Capacity Workgroup consists of representatives from the Office of Research and Development, Office of Air and Radiation, Office of Water, Office of Solid Waste and Emergency Response, Office of Environmental Information, Office of Pollution Prevention and Toxics, and several EPA regional offices. A critical area identified by the workgroup was the need for a list of analytical methods to be used by all laboratories when analyzing homeland security event samples and, in particular, when analysis of a large number of samples is required over a short period of time. Having standardized methods would reduce confusion, permit sharing of sample load between laboratories, improve data comparability, simplify the task of outsourcing analytical support to the commercial laboratory sector, and improve the follow-up activities of validating results, evaluating data, and making decisions. To this end, workgroup members formed an Analytical Methods Subteam to address homeland security methods issues. The Analytical Methods Subteam recognized that widely different analytical methods are required for various phases of environmental sample analyses in support of homeland security preparation and response: (1) ongoing surveillance and monitoring, (2) response and rapid screening for determining whether an event has occurred, (3) preliminary site characterizations to determine the extent and type of contamination, and (4) confirmatory laboratory analyses to plan, implement, and evaluate the effectiveness of site remediation.