The Deep Decarbonization Pathways Project Report calls for major increases in building and equipment efficiency to reduce U.S. greenhouse gas emissions by at least 80 percent from 1990 levels by 2050. While the U.S. Department of Energy efficiency standards program is one of the most successful U.S. policies in driving energy savings, carbon reductions, and consumer savings, it will need to be made even stronger, and an integrated suite of additional and more ambitious energy-efficiency laws and regulations at the federal, state, and local level will be needed to meet this goal. Additional action from private actors, such as utilities and businesses, will also be necessary. This Article, excerpted from Michael B. Gerrard & John C. Dernbach, eds., Legal Pathways to Deep Decarbonization in the United States (forthcoming in 2018 from ELI Press), discusses the various legal and policy pathways at the federal, state, and local levels to ensure that the energy efficiency of residential, commercial, and industrial products continues to improve at the scale and speed necessary to meet the “80% by 2050” goal.