This paper describes the role of agricultural extension in sub-Saharan Africa, and gives a typology for types of extension, which includes the basic forms of public top-down, participatory, and private. An overview of the evidence base for successes or failures of various models is given, which shows that evidence has been mixed on some of the major extension models in SSA, and that it is difficult to show impact for extension. There is also a lack of evidence on some of the newer models, extension reforms, and pluralistic models that involve many different extension providers. In general, though, problems in extension systems were due to a combination of a lack of relevant technology, failure by research and extension to understand and involve clientele in problem definition and solving, lack of incentives for extension agents, and weak linkages between extension, research, and farmers. The current status of extension in various sub-Saharan African countries is assessed, and new models are discussed. A framework for designing and analyzing extension systems is briefly described. Finally, future prospects for extension in sub-Saharan Africa are discussed.
Keywords: Extension, Sub-Saharan Africa, advisory services, impact, models