Symposium HH, "Advances in Materials for Nuclear Energy," was held Nov. 25-30 at the 2012 MRS Fall Meeting in Boston, Massachusetts. As the world faces steadily rising energy demand and cost, nuclear energy produced by fission and fusion reactors is increasingly recognized as an economically viable and carbon-neutral alternative to fossil energy sources. With new reactor concepts pursuing passive safety mechanisms and better performance, the behavior of structural materials and fuel is at the forefront of challenges in the development of promising reactor ideas. Accordingly, the research and development activities in nuclear materials and fuel areas have substantially increased over the last few years. The goal of this symposium was to provide a forum for the discussion of materials limitations and new developments in the field of nuclear fission and fusion energy on an experimental and modeling platform. This volume represents recent advances in materials for nuclear energy applications.