During the recent decade the organizations of agricultural producers in the national dairy, potato, egg and mushroom industries implemented various pre-production and production restriction practices with the primary objective of agricultural output price stabilization. The buyers of the affected agricultural commodities have challenged the legal status of production restrictions in a number of recent and current antitrust lawsuits, arguing that the Capper-Volstead Act, a limited antitrust exemption, does not protect production restrictions. Using the theory of oligopoly, this research evaluates potential market effects of agricultural production restrictions by comparing the organizations of agricultural producers with classic illegal cartels, which harmful effects antitrust law aims to prevent. The available empirical evidence on the market and price effects of agricultural output control practices is discussed in light of the theoretical analysis.