Propensity For Change Among The Rural Poor in the Mississippi Delta: A Study of the Roots of Social Mobility: Agricultural Economic Report No. 85, June, 1970. Economic Research Service, USDA, in cooperation with Louisiana State Agricultural Experiment Station, Louisiana State University. Available free from Office of Information, USDA, Washington, D.C. 20250. For sale by Superintendent of Documents, Washington D.C. 20402, 22 p.