Low soil fertility is a major factor limiting smallholder farming in western Kenya. A soil management project began in 1994 to address the problem at two KARI Centres in the region; KARI - Kisii and KARI - Kitale. The project is supported by the Rockefeller Foundation both financially and technically. The approach adopted for implementation of the project activities involves Farmer Participatory Research. This approach enables farmers to have a greater influence on priorities and decisions of research to be undertaken because they are actively involved in the whole research process. Multidisciplinary teams involving several institutions participated in the implementation of the project. Preliminary results indicate that the use of organic manures is more beneficial when combined with inorganic fertilizers. Combining stone lines and grass strips can be an effective method of controlling run-off, especially during the establishment of the grass strips. Suitable crop and forage varieties have been identified and the potential of mucuna and sunnhemp as green manure legumes has been confirmed.