This chapter summarises the major lessons learned from five country case studies (Ghana, Mali, Senegal, Tanzania and Zambia), which the OECD Development Centre conducted during 2006 and 2007. The aim of the country studies was to examine donor and government efforts to promote agro-based private sector development. In the five countries, the transformation of agriculture and the development of agro-based industries have yet to materialise. The agricultural potential of the five countries is largely untapped and the sector is characterised by a dualistic structure, with few commercial farmers and a large majority of smallholders, the latter mostly engaged in subsistence agriculture. Yields for cereals, roots and tubers have actually stagnated, mirroring similar trends in other African countries. However, while food crop productivity has been stagnating, horticultural exports have emerged as a new driver of agricultural growth. Donors have played an important role in the promotion of the horticultural sector, especially in Senegal and more recently in Ghana. Contract farming (e.g. outgrower schemes) has proved to be an effective mechanism for involving smallholder farmers in export crop production and achieving economies of scale. Also donors are increasingly adopting a value chain approach and trying to tackle various bottlenecks at once. Yet, harmonisation and alignment is less advanced in the agricultural sector than in the social sectors. The predominance of stand-alone projects and the involvement of several line ministries (e.g. agriculture, infrastructure, land, trade) dealing with agriculture make progress difficult. Furthermore, the market potential of staple foods should not be overlooked. Traditional food crops are often better adapted to local agro-ecological conditions, and rising local and regional demand presents an opportunity to expand production and develop food-processing industries. Currently donors and governments tend to put too strong a focus on export crops and too little on staple foods.