Without question, agricultural extension is now back on the development agenda. The acknowledged failure of the T&V extension model in Asia and Africa in the late eighties and early nineties has stimulated debate on extension reforms and new extension models such as Farmer Field Schools. Today extension reforms are underway in many countries in Asia and Latin America and to a lesser extent in Africa. The purpose of this review is to summarize the literature on the role of agricultural extension systems in helping smallholder farmers in Africa and Asia increase agriculture production and their livelihoods.