Book excerpt: This report presents the findings of an environmental performance assessment that covered the Greater Mekong Subregion (GMS) during 2006–2016. The GMS Environment Operations Center conducted the assessment, using the driver–pressure–state–impact–response model to examine the consequences of rapid economic development in the subregion, identify the major natural resource and environmental issues, and determine the effectiveness of responses by the GMS member countries. During the assessment period, the GMS Core Environment Program supported country efforts to address the subregion's natural resources and environmental management challenges with its goal of creating an "environmentally friendly and climate-resilient GMS Economic Cooperation Program."