A central challenge to determining the sustainability of shale gas is the manner in which energy and climate change issues have been framed by the gas industry, governmental decision makers, and the public. The dominant perspective on energy focuses on the supply side—we always think we need to find and then use more energy, but we almost always assume that the efficiency resources are used up and unavailable. The evidence suggests that, yes, there have been substantial energy efficiency improvements in the U.S. economy since 1970. More critically, however, a large number of studies document the vast amount of additional energy efficiency that can still be extracted from the U.S. economy in cost-effective ways that not only reduce costs and pollution but also produce additional jobs and economic activity. In short, energy efficiency is the most sustainable energy source, producing a variety of economic, social, and environmental benefits. When the adverse effects of shale gas development are added, the comparative benefits of energy efficiency are even greater. But changes in law are needed to even the playing field—removing financial incentives for fossil fuels and disincentives for energy efficiency—so that energy efficiency can compete effectively and produce more positive outcomes.