The viability of advanced Pb- or Pb-Bi-cooled fast reactor systems will depend on the development of classes of materials that can operate over the temperature range 650-1200°C. We briefly review the current state of the technology concerning the interaction of Pb and Pb-Bi alloys with structural materials. We then identify the key challenges to successful use of materials in these systems and suggest a path forward to the development of new materials and operating methods to allow higher-temperature operation. Our focus is on the necessary trade-offs that must be considered and how these trade-offs influence R&D choices. Our analysis suggests that three classes of materials will be needed for successful deployment of a lead-alloy-cooled reactor system. A lower-temperature qualified material will be necessary for the pressure boundary. The structural and cladding materials will require 1000°C- and 1200°C-class materials. The 1000°C-class material will be exposed to the 1000°C coolant. The 1200°C-class material will be required for the cladding and structural materials in the core region. The higher-temperature material will be required to accommodate anticipated temperature transients from potential accident scenarios, such as a loss of flow.