As funding for agricultural research becomes increasingly scarce in many countries, research administrators have come under heightened pressure to ensure that available resources are used efficiently. The need to demonstrate accountability has generated increased interest in research impacts assessment methods and motivated a large number of empirical studies designed to determine whether agricultural research programs are having their intended effects. Many of these studies have used some type of benefit-cost framework to calculate economic rates of return to research investments. Benefit-cost analysis typically involves measuring the diffusion of innovations produced by a research program and calculating the economic benefits resulting from their adoption