This report details energy efficiency targets and developments in five countries in the Greater Mekong Subregion (GMS): Cambodia, the Lao People’s Democratic Republic, Myanmar, Thailand, and Viet Nam. The GMS countries envisage substantial energy efficiency savings over the next 15 to 20 years, with overall energy efficiency savings amounting to almost 60 million tons of oil equivalent annually by 2030. GMS countries project that their energy needs will double or triple over the next 15 years and greater energy efficiency offers a win–win public–private sector partnership for reducing unsustainable reliance on high-carbon fuels.