Can the global use of nuclear energy be expanded enough to make a significant contribution to mitigating climate change while simultaneously reducing the risks of proliferation, terrorist access, nuclear accidents, and nuclear war? Expanding nuclear capacity worldwide based on large centralized facilities (e.g., generating capacity greater than 1 gigawatt) poses challenges and risks due to the large capital outlays, potential safety issues, negative public opinion, and persistent concerns about proliferation–that is, the intentional misuse of nuclear technology and material. Small modular reactors (SMRs), defined as units with a generating capacity of less than 300 megawatts that are delivered to the site fully assembled, may represent a viable alternative to large reactors since they require smaller initial capitalization, better match existing demand for energy and capacity requirements, may be easier to site, and may engender less public opposition. This symposium evaluates the opportunities and challenges associated with SMRs. It will address the technical challenges for SMR designs, the creation of market incentives that can promote innovation and diffusion of SMRs, and the national and international policy and regulatory environments to ensure safety and proliferation resistance.