From 1940 to 1970, Parsons worked with the United Nations Food and Agriculture Organization, the Marshall Plan, the Ford Foundation, and the U.S. Agency for International Development conducting research in Europe, Asia, Africa and Latin America, with a special focus on land tenure and land reform and their economic implementations.
Parsons wrote "The John R. Commons' Point of View", Journal of Land & Public Utility Economics, 1942.
Parsons was one of the first U.S. agricultural economists with a professional concern and commitment to the study of economic development.
Together with Raymond Penn and Philip Raup, he edited the proceedings published as Land Tenure and Related Problems in World Agriculture, University of Wisconsin Press, 1956.
Parsons' responsibility was to build a department of agricultural economics, train students, and teach courses and seminars.