Materials research is recognized as a key to the development of an economic and reliable fusion reactor. The environment in which materials must perform in a magnetic fusion reactor is established and general criteria for selecting structural and special purpose materials are summarized. On this basis, the U.S. program in materials development for fusion is described. Key program elements include the development of alloys for use as structural materials, the study of fundamental processes central to radiation damage analysis, the development of special purpose materials, the study of plasma materials interactions, the development of coatings and special material surfaces, and the development of components capable of handling high heat and particle fluxes that are incident on components like limiters, divertor target plates, neutral beam heat dumps, and other in-vessel components in fusion reactors. The relationship of the materials program to the rest of the national fusion program is discussed.