The Experimental Breeder Reactor-II (EBR-II) was a 62.5 MWt±20 MWe sodium cooled fast reactor that was operated successfully for 30 years. Over its period of operation a wealth of fuels and materials information originated from EBR-II. Several missions were conducted in EBR-II, all of which yielded new and valuable additions to the world's knowledge base for nuclear materials. Some of the ®rst pioneering experiments on irradiation eects in stainless steels were conducted in EBR-II. Later, practical manifestations of enhanced irradiation creep, swelling, and loss of ductility were experienced on EBR-II components. In addition, for a period of more than 15 years, the EBR-II reactor would become the primary irradiation facility for all fast reactor fuels and materials research and development. Both the initial mission and ®nal mission for EBR-II (the Integral Fast Reactor Concept, IFR), involved the remote reprocessing and irradiation of fast reactor metallic fuels. The fuels and materials information gleaned from these missions will be summarized with the intent of portraying a sample of the valuable legacy that EBR-II contributed to the world's store of nuclear fuels and materials knowledge.