Trees, crops, and livestock are integral parts of the complex farming systems on Nepalese hillsides. Any strategy for soil fertility improvement will take account of the interactions between these components, both on private farmland and common property and in public access forest and grazing areas. This requires a less restricted definition of the scope of agro-forestry than has often been applied previously. Agro-forestry can contribute to soil fertility improvement through increasing the quality and quantity of fodder and hence livestock manure, providing biomass for composting and slowing the loss of nutrients through runoff. Socioeconomic contextual factors that influence the introduction of agro-forestry innovations include the distribution and fragmentation of landholding, the relative importance of agriculture in household livelihoods, and the gender division of labor and management responsibilities within households. Studies of socioeconomic processes relating to the generation of local knowledge and its distribution, and of socially differentiated communication patterns within and between rural communities, can enable researchers to better focus their efforts. Examples from Nepal are presented and their implications for research design, method, and process, and for dissemination are explored.