Minimum energy efficiency standards are regulations that require products to meet specific energy efficiency requirements. Standards have been adopted in 17 countries plus the European Union. Standards have been set on more than 35 products, with refrigerators, air conditioners, ballasts, and freezers being the most common. Based on the available evidence, standards appear to be a very effective energy-saving policy. They have reduced energy use substantially in the United States and made good initial progress in other countries. The standards that have been implemented thus far appear to be cost effective to consumers and result in minimal adverse impacts on manufacturers. Available evidence indicates that the costs of actually implementing standards are commonly less than estimates made by manufacturers and government agencies during the standard-setting process. Standards are frequently a useful complement to other policies such as product labeling, incentives, and voluntary agreements. However, standards are not appropriate for all products and situations.