The evaluation of the environmental impact and treatment requirements of in situ oil shale waters depends on precise and accurate data from the laboratory. Standard laboratory methods perform well on typical waters and wastewaters (U.S. Environmental Protection Agency, 1979; American Public Health Association, 1975). But oil shale waters are unusual because of high organic content, high salinity, color, and other properties. Many standard laboratory methods, as well as research methods, were found to have considerable imprecision and inaccuracy when used to analyze process waters from the Omega-9 oil shale experiments (Fox, 1978). This project was undertaken to determine if the problems found in the Omega-9 study were common to other oil shale waters. The design of the project involved the careful selection of water types, number of laboratories, number of replicate analyzes, number of water quality constituents, and number of standard analytical methods. The project has been designed to produce useful information on the variation due to analytical methods. The approximately 11,000 data compiled during the project were analyzed statistically and graphically, and the results were expressed as the within-lab precision, between-lab precision, and accuracy of the analytical methods used in the analysis of oil shale condensate and process waters.