This paper uses the materials cycle to assess the implications for science and technology of finite and increasingly costly supplies of resources. The analysis is based upon the economic view that lagging productivity and increases in materials prices pose a more serious threat to resource adequacy than depletion. The resource question is discussed in terms of development of domestic minerals, trade in raw materials and finished goods, environmental constraints, recycling, and investment in materials industries. The implications for science and technology of each of these factors is considered in terms of basic trends. The paper concludes that efficient use of materials, defined not only in terms of quantity of material per functional output, but also value added per unit of input offers the best prospect for resource adequacy in the foreseeable future. According to this view, the Nation needs to devote more of its scientific and technological resources to studies of corrosion, wear, degradation, and failure of materials, as well as to efficient methods for nondestructive testing of materials. Improved understanding in these areas would conribute to the development of a scientific basis for the most efficient use of materials in terms of performance and expected lifetime.