A number of collaborative research projects between Belgium, Canada, France, Japan, Sweden, Switzerland, the United States, and the Federal Republic of Germany are now in progress to test the relative surface reactions of nuclear waste glasses under a wide variety of simulated repository conditions. The studies include 1-, 3-, 6-, 12-, 24-, and 32-month deep burial in granite boreholes in the Stripa mine in Sweden at 90 and 10°C. Nearly 2000 interactive interfaces are being studied in salt in the Waste Isolation Pilot Plant site in the United States. Several glasses from these tests are also being evaluated in clay in Belgium. Comparisons of the simulated burial conditions with glasses containing radioactivity close to that expected for commercial operations at LaHague, France, are being made by a Japan-Sweden-Switzerland consortium with collaboration from the Commissariat à l'Energie Atomique, Marcoule and the Hahn Meitner Institute, Berlin. These studies are leading toward an international consensus on the relative performance of high-level waste forms including borosilicate glasses, waste packages, and repository variables.