For decades, there has been significant investment in the development of agricultural technologies that aim to increase productivity of smallholder farms in Africa. At a macro-level, however, farm output and productivity have stagnated and poverty rates have remained stubbornly high, even increasing in some areas. It is widely acknowledged that policy and infrastructural constraints play a large role in reducing incentives for farmers to invest in agriculture. Yet the fact that farmers have made some investments and that some progress has occurred suggests that characteristics of the technologies themselves, or the way in which they are promoted, also facilitate or inhibit wider adoption and impact. This research report, part of a set of studies on the impact of agricultural research on poverty led by IFPRI, analyzes the adoption and impact of agroforestry techniques for soil fertility enhancement in one of the poorest regions of the world—the western Kenyan highlands. It further examines the role that government and nongovernmental organizations and their different dissemination methods play in reaching potential users and helping them understand and use this knowledge-intensive technology. In this study, the researchers have used quantitative and qualitative research methods to make discoveries and develop insights that neither method alone could accomplish. The authors find that improved fallows and biomass transfer systems are attractive to the poor because they are low in cost and provide noticeable increases in crop yields. Lower and higher income groups in the study villages use these systems in similar ways—this is not the case for fertilizer use—but the small farm sizes of the region limit the impact of this technology. The size of area under these systems remains small after six years of dissemination, indicating that yield improvements do not translate into significant household-level welfare impacts for the most part. Maintaining information flows is a challenging task with such high rates of poverty and the continuous search for livelihoods on and off farm. Persons in close contact with development organizations increase their knowledge of soil fertility management, but villagers noted problems with the quantity and quality of information. Different methods for disseminating knowledge have strengths and weaknesses with respect to reaching poor farmers and women, and this has implications for social capital. It is challenging to reduce short-term poverty rates in highly populated areas where farm sizes have decreased to less than one hectare. Adverse shocks are ubiquitous and they almost always deplete household asset bases. The authors do not find any single occupation or investment that always improves welfare. Thus, the study confirms in a clear way that poverty reduction will require sets of interventions and greater understanding of their sequencing and integration. Low-cost methods for raising soil fertility can be coupled with other feasible enterprises for poor farmers, such as the use of improved maize varieties that are resistant to streak virus and the increased planting of higher value crops like kales and climbing beans. Greater investment in poultry or ruminants and in fruits or woodlots are also within the capacity of poor households. The spread and speed of such investments would need to be underpinned by increased access to capital or credit, which is very scarce in the study site.