The need for technological transition and the context of the privatization of public research funding both challenge the evolution of methods to assess the impact of research in the agricultural and food sectors. We analyze this evolution through a literature review and an examination of a range of case studies on research completed in developing countries. In the first part, the results stemming from the former analysis question the controversies raised by quantitative approaches. In view of these controversies, we then examine the methodological innovations taking place in a qualitative approach. A survey of case studies ultimately helps to characterize the strategic resources that research generates with a view to improving its impact on innovation and development.