Rapid rates of urbanization in much of the world will lead to an unprecedented expansion of the built environment. The choices being made today about how to build, design, and operate these buildings will affect urban services and livability for decades. Efficient, high-performance, and productive buildings will be a major factor in creating sustainable cities, which, in turn, contribute to sustainable development goals at the regional and national level. Local governments can influence the efficiency of new and existing buildings in their communities as owners/investors, conveners/facilitators, or regulators. They can deploy a variety of policy options, ranging from setting targets and leading by example to implementing codes and performance systems, providing financial and non-financial incentives, and supporting stakeholders in buildings in ways that improve the business case for pursuing or financing energy or water efficiency. This guide provides local governments and other urban leaders in cities around the world with the background, guidance, and tools to accelerate building efficiency action in their communities. The primary intended audience is local government officials in urban areas. Efficient buildings—those that make highly productive use of natural resources—are vital to achieving sustainable development: They align economic, social, and environmental opportunities, creating so-called “triple bottom line” benefits. Efficiency goals should connect to specific priorities of local governments and communities, ensuring that the government and citizens optimize, minimize, or manage water, energy, and waste, as appropriate. Policies and programs can support efficient use of resources to provide heating, cooling, lighting, and domestic water, as well as to operate appliances and equipment installed or used in a building. This report serves as a reference guide for identifying and prioritizing appropriate actions to advance efficiency in both communities and organizations. The options for local government actions to improve the energy efficiency of the built environment fall into eight categories: ACTION 1: Building efficiency codes and standards ACTION 2: Efficiency improvement targets ACTION 3: Performance information and certifications ACTION 4: Incentives and finance ACTION 5: Government leadership by example ACTION 6: Private building owner, manager, and occupant engagement ACTION 7: Technical and financial service provider engagement ACTION 8: Working with utilities