The United States, EURATOM, Japan, and Swltcerland have collaborated alnce 1978 In development of superconducting toroidal field colli for fusion reactor applications.The United Stares provided a test facility and three coils; the other participants, one coll each. All colls have the same interface dimensions and performance requirements (stable at 8 T), but Internal design was decided by each team. Two D.S. coll teams chose bath-cooled KbTl, 10-kA conductors. One developed a NbjSn conductor, cooled by internal flow, rated at 18 kA. All U.S. coils have diagnostic instrumentation and imbedded heaters that enable stability tests and simulated nuclear heating experiments. In single-coil tests, each coil operated at full current in self-field (6.4 T). In si*-coil tests that began In July 1986, one D.S. coll and the Japanese coll have been successfully operated at full current at 8 T. The other colls have operated as background colls while awaiting their tun as test coil. Coil tests have been Informative and results gratifying. The facility has capably supported coil testing and its operation has provided information that will be useful in designing future fusion systems. Coil capabilities beyond nominal de6lgn points will be determined.