A repository of 14 gaseous organic compounds at parts-per-billion (ppb) levels in compressed gas cylinders has been established by the U.S. Environmental Protection Agency (EPA). The primary objectives of this on-going project are: (1) to provide accurate gas mixtures to EPA, state/local agencies, or their contractors for performance audits to assess the relative accuracy of source measurement systems during hazardous waste trial burn tests and ambient air monitoring programs; (2) to verify the manufacturer's certified analysis of the multi-component gas mixtures; (3) to determine the stability of the gas mixtures with time; and (4) to develop new audit materials as requested by EPA. The repository consists of two mixtures of five and nine organic compounds in aluminum cylinders in a balance gas of nitrogen. The five component mixture (Group I) contains carbon tetrachloride, chloroform, perchloroethylene, vinyl chloride and benzene. The nine component mixture (Group II) includes trichloroethylene, 1,2-dichloroethane, 1,2-dibromethane, acetonitrile, trichlorofluoromethane, dichlorodifluoromethane, bromomethane, methyl ethyl ketone and 1,1,1-trichloroethane. To date, 20 performance audits have been initiated and 12 are complete. The results of these audits and a description of the experimental procedures used for analyses and available stability data are presented in this Status Report 1.