The public-sector provision of agricultural supplies and marketing is largely a thing of the past in Africa; however, private sector traders have not yet filled the gap left by the state, especially where smallholder farmers are concerned. In some cases, groups of farmers can purchase supplies and market their produce profitably. This article describes research carried out jointly by the Natural Resources Institute and the Plunkett Foundation, involving visits to five countries in sub-Saharan Africa during 1994–6, directed at identifying the characteristics of sustainable farmer-controlled enterprises in surplus-producing areas. It also aimed to define programming features which would contribute to a sound support policy for this sector – an area in which international donors and NGOs now take a leading role. This article highlights the research team's findings, and their implications for donors seeking to promote farmer groups.