Energy issues have once again emerged as central public policy themes. In particular, energy efficiency and smart grid technologies are emphasized significantly in recent federal legislation, such as the American Recovery and Reinvestment Act and federally proposed climate legislation. I describe research and analytical efforts to inform federal climate and energy policy decisions in my role as an American Association for the Advancement for Science (AAAS) Science and Technology Policy Fellow positioned at the Climate Protection Partnerships Division, U.S. Environmental Protection Agency. In the first part of my talk, I review the results of an internal effort to understand the potential for reducing energy consumption through increased end‑use energy efficiency. A meta‑analysis of recent studies of U.S. national and regional energy efficiency potential in buildings and industry was conducted. While it is challenging to compare the results from these studies, due to differing assumptions, methods, and data, they provide a range of what portion of energy consumption can be offset through end use efficiency. I discuss the estimated reductions in electricity and natural gas use and identify methodological changes that may improve the estimation of energy efficiency potentials. In the second part of my talk, I highlight results from efforts to incorporate energy efficiency in the agency's climate policy analysis; this work was published in the EPA's analysis of the House approved Waxman Markey climate bill. Lastly, I discuss a framework for thinking about “smart grid” technologies from a clean energy perspective and issues from an environmental policy perspective. I conclude my talk with insights on the types of analytical and research opportunities that can help to better understand the nexus of energy efficiency, smart grid, and climate change mitigation.