Getting farmers to adopt new technologies to address soil erosion and fertility problems is not easy. In Vietnam, a multidisciplinary research project to improve soil management in traditional mountainous agricultural farming systems managed to attract farmers¿ interest and stop soil erosion. This success stems from encouraging farmers, extensionists and researchers to jointly define and implement the project. Their different aims could be followed simultaneously: scientific results for researchers, better agricultural practice for extension workers, and economic success and free choice for farmers.