The irrigation and drainage systems in the Red River Delta in Vietnam were designed and constructed in the 1950s and 60s. These systems are well established and provide water to virtually all of the irrigable land in the Delta. The land is cropped intensively: on average just over two crops a year. The irrigation and drainage systems are complex: dual purpose channels and pumping stations are used. In the 1990s, the systems were rehabilitated and upgraded. A review showed that irrigation projects performed reasonably well, but the two core drainage projects performed less than anticipated. In the Red River Delta, with its low elevations, drainage rather than irrigation is often the limiting factor affecting agricultural production. To investigate these constraints in more detail, a participatory research study on the effectiveness of drainage was conducted in two drainage areas in the Red River Delta. The study started with a participatory pre-investigation to identify and quantify the constraints in the functioning of the drainage systems. Next, the drainage system was modelled and computer simulations were used to develop conceptual designs to improve the functioning of the systems. Finally, recommendations to improve the institutional capacity of the drainage system management were formulated, again in close cooperation with the stakeholders. These recommendations cover a whole range of technical issues: small-scale improvements in the farmers' fields, modifications in the main and secondary drainage systems, including the control structures, up to recommendations to Irrig Drainage Syst (increase the efficiency of the pumping stations. Next to these technical innovations, recommendations to reform the complex institutional setting have been formulated.