In 1992, Cambodia, the People’s Republic of China, the Lao People’s Democratic Republic, Myanmar, Thailand, and Viet Nam established the Greater Mekong Subregion (GMS) Economic Cooperation Program with the aim of strengthening economic linkages between them and to foster the achievement of common policy goals. In the 20th anniversary year of the GMS, this second edition of the atlas illustrates the exquisite beauty, bounty, and diversity of the subregion’s natural environment, the tremendous progress made by the GMS countries over the past decades, and the need to address the increasing risks that they face.