This dissertation presents a methodology for measuring the impact of crop management research on agricultural productivity. The relationship between specific research projects and increases in producer surplus are identified. The methodology is used to derive an estimate of the return to public investment in crop management research in the Yaqui Valley of Sonora, Mexico;The impact of the crop management research effort is examined by looking at changes in producers' practices 1981-1989 using farm survey data. An examination of changes in producers' practices and modifications in crop management recommendations showed that only two practices were modified because of new research results. The quasi-rent impact of these research-induced changes in farmer practice are estimated using yield function estimation and the construction of enterprise budgets;The market setting for the case study is one of a small producing region facing perfectly elastic demand for output as well as perfectly elastic supply of production inputs. Changes in consumer surplus, therefore, do not occur and the impact on producer surplus is measured as changes in quasi-rent;Estimates of the internal rate of return (IRR) to the crop management research investment are derived under a range of assumptions about the benefit and cost streams. Under the most reasonable sets of assumptions, the IRR is estimated to fall between 16 and 26 percent;The study implies that the development of improved crop management practices can make a significant contribution to increasing agricultural productivity. One implication for the allocation of resources within agronomic research programs is that careful monitoring of farmer acceptance of research results can improve the efficiency of research investments.