Africa has experienced the least socioeconomic progress in recent decades by many measures. Poverty, disease, drought, and conflict have combined to trap many nations in endless cycles of misery and plummeting quality of life. Agriculture, one potentially significant avenue out of these cycles and Africa's largest economic sector, is burdened with significant problems. Over the last five decades, various approaches to agricultural development have been introduced with some modest levels of success. The latest extension innovation in the fight against rural poverty is the Farmer Field School (FFS), introduced to Africa from South East Asia in the early 1990s. FFS are groups of people with a common interest getting together regularly to discuss, observe, understand, and practice the 'how and why' of particular topics in agriculture. FFS are specially adapted to field study where specific hands-on management skills and conceptual understanding is required. Kenya was one of the first countries in Africa where the UN-FAO set up pilot FFS projects, many of which developed into success stories. The present study was initiated to find out how the concept of the FFS has been adopted and scaled-up, and what qualitative difference this has made in the lives of the farmers involved. This researcher is personally interested in Western Kenya because he grew up there and wants to understand its development challenges and opportunities, and the region has a significant number of agencies involved in agricultural development.;The first objective is to learn more about Farmer Field Schools as organized in this region today; the second objective is to compare some elements among the FFS in order to identify the characteristics and processes that are associated with outcomes that provide members the greatest benefits in terms of learning and sustainable livelihoods.;This study may form part of a long-term study to understand the role of FFS in changing peoples' lives from a Sustainable Livelihoods perspective. It involved the collection of qualitative data through semi-structured interviews and focus groups from four FFSs that were then be compared on the basis of group development and maturity, and the groups' contribution to the sustainability of members' livelihoods. Contrary to the expectations at the beginning of the study, the groups reflected greater variation than anticipated. While it appeared that groups with more years of experience were more independent than newer groups, the former had not yet initiated other groups. But there was evidence that the more experienced groups had helped to promote the spread of new technologies and methods to other groups and individuals. Secondly, groups that were well funded were not always more independent than those that were poorly funded or self-financed. Lastly, groups with initial high social and human capital were not necessarily more mature and independent than those that were formed for the sole purpose of the field school. This probably calls for the need to distinguish between pre-existing social capital within a community before the residents form an action group and the social capital that is created when they form the group. There is a significant role that the facilitator plays, and while group leadership influenced the perceived performance of the group, the level of literacy of the leaders was not a predictor for group performance. The style of leadership and experience in leadership roles determined how the groups responded to their leaders.;Based on these observations, group viability is largely influenced by members' other primary occupations, external facilitator skill and commitment, and proximity of the members' homes relative to each other and relative to the experimental farm. This implies that planning for a successful field school should include a process for selection of members whose primary occupations as well as relative proximity to other potential members' farms and to the experimental farm would not keep them away from participating in the field school activities as needed, and the designation of a well-trained and committed facilitator to the group.;A more thorough analysis of such groups can help one predict the success or withering of a group with some degree of certainty, allowing that memberships within groups can always change and in turn shift the perceived trajectory of a group's fortunes.