Thirty-eight percent of all farmers belonged to marketing/farm supply cooperatives in 1978. Another twenty-five percent were nonmember patrons but contributed little to cooperative volume. Cooperative membership was highest among dairy farmers and large farm operators and lowest among livestock farmers and small farm operators. Most cooperative members, however, were livestock farmers and operated medium sized farms. Member patrons marketed most of their major crops and purchased most of their major farm supplies cooperatively. Member patrons with the largest sized farms purchased a smaller portion of their farm supplies cooperatively than did the smaller farm operators.