The institutional diversification of agricultural research, the appearance of new institutional actors (i.e. NGOs, the private sector, universities), and the increasing complexity and costs of agricultural research as a consequence of the very rapid development in the new areas of science, are leading to significant changes in the organizational structure of agricultural research. We are witnessing a clear evolution from an organizational model that was characterized by the very predominant role played by one large public research institute, a National Agricultural Research Institute (NARI), to an organizational model based on a diversified institutional infrastructure, where a range of institutions play different but complementary roles in the process of generating, adapting, disseminating and using technology to improve the quality of sustainable livelihoods in the rural sector. This second model is given the generic name of National Agricultural Research Systems (NARS).