Lessons learned from A.I.D.'s efforts to strengthen developing country agricultural research capacities are assessed. The assessment is based on the findings of impact evaluations of AID-funded research projects in Kenya, Central America, Korea, Guatemala, Nepal, Thailand, Tunisia, and West Africa; a review of other project evaluations; and a 6/82 AID-hosted international conference (proceedings appended). Key findings and recommendations for future A.I.D. efforts fall into four categories. First, a genuine, long-term commitment to agricultural research by the host government determines research sustainability and indirectly the use of research findings. Such support will be more likely if there is continuous dialogue among politicians, administrators, and researchers, and if the government receives a clear demonstration of the potential benefits of the research and agrees with the research institution on the latter's mandate and authority. Second, since host government policies and infrastructure partially determine farmer adoption of new technologies and the availabiliy of needed support services, research programs should be selected within a broad rural development policy and planning framework. Also, technological changes can sharpen inequity among rural households if technology adoption depends upon a resource distributed unequally. Third, research programs can only help increase food production if their designers are aware of existing farming systems and local agro-ecological and economic conditions and the resources available to farmers. This will demand linkages among researchers, extensionists, farmers, concerned government entities, and agricultural training institutions. Fourth, the sustainability of research demands efforts to retain skilled personnel. To this end, A.I.D. training should complement technical assistance and be adapted to a country's real needs and capabilities, and returning trainees should be given adequate incentives. National research institutions should maintain an active network of information exchange with other national and international institutions. Most of the above issues, it is concluded, share a common solution - coordination and information flow among all concerned.