The Environmental Methods Testing Site (EMTS) Project is being conducted by the Environmental Protection Agency with the cooperation of the state of Georgia, the state of Tennessee, Hamilton County, Tennessee, and the city of Chattanooga. The concept is to establish one well-characterized site, designated as the Chattanooga Metropolitan Statistical Area, at which to conduct a series of studies designed to improve environmental monitoring methods and methods for assessing human exposure to toxic substances in the environment. The project, planned to span a 5- to 15-year period, is being conducted in support of the Toxic Substances Control Act of 1976. The Chattanooga area is well suited as a site to conduct human exposure methodology studies. Site users have the support of local government and of EMTS Project participants who provide a management team, information gathering services, computerized data management and analysis, and quality assurance assistance. The Chattanooga area provides a hospitable climate, a population and geographical size allowing statistically valid sampling of subpopulations, isolation from other cities, a diverse industrial base, a large existing data base, and modern technical and logistical support facilities.