Energy and its associated carbon emissions have become major strategic issues affecting the overall development of human society and the global political and economic landscape. As the world's largest developing country, China faces even more severe energy challenges. Energy conservation and substantial improvement in energy efficiency represent an extremely important and effective pathway for China to address the challenges of energy and climate change. This report comprehensively summarizes and analyzes the energy development status of the world and China, proposes the connotation and measurement methods of energy efficiency, and investigates the impact of economic structural changes on aggregate energy efficiency, urban–rural and regional characteristics of residential energy consumption, energy efficiency in key energy-consuming sectors, the effect of prices on oil demand, policy simulation and analysis of energy efficiency policies, and discusses ten important issues concerning opportunities for improving China's energy efficiency. In response to changing international and domestic energy economics and climate policy situations, each volume of the China Energy Report selects a different theme and conducts targeted research, emphasizing empirical and policy-oriented analysis, with the aim of providing a scientific basis for relevant policy decisions. China Energy Report (2010): Energy Efficiency Research is the third volume in the China Energy Report series.