This paper describes the current state of energy efficiency financing, highlighting what is and isn’t working, while offering a look at the future of the industry. The US energy efficiency finance market represents more than $100 billion in annual investment, with particular strength in segments like green buildings and cars, ENERGY STAR®–certified IT equipment, and energy service companies (ESCOs). On the other hand, low- and moderate-income households, multifamily housing, many state and local governments, and the small commercial market remain underserved and credit challenged. Green bonds, better technology, new financing methods, and more sophisticated evaluation are keys to future growth.