In the Mekong Basin, rice plants have low yields because of degraded soils, fresh water is becoming scarce, and rice cultivation consumes a lot of water. Beijing-directed rules to govern the river and its plan to build cascade dams upstream have weakened the Mekong River. The Mekong River Commission was established in 1957, but for over 50 years, the Commission still has only Laos, Cambodia, Thailand, and Vietnam as members. To confront all these troubling trends and challenges and the sustainability of the region, riparian countries in the lower Mekong areas have sought partnerships with support from the USA, Japan, Australia, and Korea. Many water development projects in the Mekong Basin have been researched and implemented by bilateral, transboundary, regional, and international collaborations. Although the collaboration is still not holistic as expected, increasing regional and international collaboration projects conducted recently have provided the bright potential for integrated sustainable water resources development and management in the Mekong Basin. A synthetic review of previous water development projects within the Mekong Basin in this chapter introduces an overview of opportunities and challenges and implies lessons for further water development projects in the future among riparian countries in the Mekong Basin and other transboundary river basins in the world.