This study estimated rates of return to public investments in human and research capital (formal schooling and extension and vocational agricultural education) in the United States agricultural industry. (Southern states were excluded because of demographic and educational factors that would have biased the variables.) Output per farm was defined in terms of human capital, research at state agricultural experiment stations, and inputs of land, labor, machinery, other expenditures, and fertilizer. The lag distribution of research was identified with the rate of adoption of hybrid corn in corn belt states. Values of marginal product ranged from $0.25 to $0.61 per dollar per year (schooling), $4.96 to $19.86 (extension and vocational agricultural education), and $5.81 to $15.28 (research). Ranges for internal rates of return were 9.6% to 61%, 196% to 636%, and 24.6% to 43.1%, respectively. Conclusions justified additional investments in these kinds of education and research. (author/ly)