Increases in energy-use efficiency have made impressive contributions to both economy and environment over the last two decades, but the rate of improvement has slowed and energy-efficiency continues to be a controversial subject. We explore the genesis and character of the energy-efficiency debate and assess the roles of market forces, government intervention, and technological innovation in determining future progress, We discuss the prognosis for utility energy-efficiency programs, which are imperiled by the current trend to utility deregulation. We note that decreasing energy prices have weakened the earlier economic stimulus to energy efficiency and discuss the strong driving force that has arisen from environmental issues. We examine the proposition that innovation stimulated by R&D investment has been a key ingredient in the development of energy-efficient technologies and assert that the continuing development of a knowledge base to assure future innovation requires a strong government/private-sector partnership.