Energy efficiency can get us about half of the way to long-term climate goals. Traditional energy efficiency strategies — vehicle and appliance efficiency standards, building energy codes, utility energy efficiency pro-grams and Energy Star — can provide about half the achievable efficiency savings (i.e., savings of about one-quarter of projected 2050 energy use). However, these strategies can benefit from a variety of improvements, and other programs and policies addressing buildings, transportation and industry can achieve substantial additional savings. These efficiency policies can be combined with strategies involving no-and low-carbon energy sources to put the United States on a trajectory toward meeting long-term energy and climate targets.