Cocoa is produced almost exclusively by developing nations in the tropics. Although it is in many ways a suitable crop for small farmers, yields are seriously reduced by several major pests and diseases. This paper identifies the major constraints, summarizes the present state of knowledge, and suggests priorities for research that would be expected to have the greatest impact at the farm level. Financial constraints and thus lack of continuity in research have hindered progress. The botany, historical development, social aspects, and environmental requirements of cocoa are covered. The agronomy section deals with rehabilitating old cocoa, the role of cocoa in farming systems, and the general husbandry of the crop. This is followed by discussion of cocoa physiology, and the relation of shade and nutritional requirements. There are both economic and social constraints to the adoption of more sophisticated farming systems by small farmers. Research is required to improve current chemical and phytosanitary control measures. While breeding for resistance is the ideal long-term solution, there are many difficulties. Pest management in cocoa is generally inadequate.