[en] The objective of U.S. Breeder Reactor Programs associated with primary circuit structural materials is to develop the design data base and associated design technology on existing commercially available materials as well as new alloys. This will permit economic operation of components at acceptable levels of plant availability and at up to 40-year lifetimes for inaccessible components. Long-term component reliability, elevated-temperature service within the creep range, and resistance to sodium attack and irradiation damage, along with design in compliance with ASME Codes and RDT Specifications, have required that the U.S. programs be directed toward contributing knowledge in a number of areas. These areas, relating to material deformation, failure modes, compatibility, fabrication, long-term behavior, irradiation damage, and availability will be discussed. The U.S. Structural Material Programs concerned with primary-circuit components will be reviewed, and their current and future contributions to knowledge of these areas will be explained