The "Downstream Mekong River Wetlands Ecosystem Assessment" is one among various sub-global assessments worldwide within the Millennium Ecosystem Assessment (MA). The objective of the MA is to conduct an integrated assessment on consequences of changes of ecosystems to human wellbeing and to analyze available responses in order to strengthen the conservation of ecosystems as well as their contribution to human needs. The project "Downstream Mekong River Wetlands Ecosystem Assessment" has conducted such activities as follows: - Assessment on condition of ecosystem services, including provisioning services (food, medical plants, biodiversity, fuel materials, water, ...), regulating services (climate regulation, water regulation, ...), cultural services, and supporting services (soil formation, habitats); - Assessment on trends of ecosystems and their services in the past 10 years and to the year 2010; - Identification of direct and indirect drivers of ecosystem service changes. - Review of impacts of ecosystem changes as well as of potential responses. This monograph is compiled from the final report of the Downstream Mekong Wetlands Ecosystem Assessment.