The United States is at an important crossroads in its management of high-level radioactive waste (HLW). It is presently in the process of changing over from a strategy that was developed during World War II, which involves storing HLW in a relatively mobile liquid form, to a strategy of the 1990s, which involves removing and isolating potentially harmful radionuclides and immobilizing them into solid and inert forms, more specifically, borosilicate glass. The resulting waste glass products will then be permanently disposed of by deep burial, within stable geologic formations, where they become one element of a multibarrier waste-isolation system. This barrier system is designed to retain radionuclides so they can be permanently isolated from the public and from the accessible environment. Important contributing factors to the success of this strategy include the excellent stability and technical performance of waste glass forms and the ability of the glass, as well as waste package materials, to retain radionuclides even when exposed to potential leachants within a repository environment.