Fisheries are paradigmatic of renewable resources because of their ecological delicacy, their vulnerability to the indirect effects of economic activity, and, above all, their nonexclusive or “common-property” nature. In this article, Professor McEvoy shows how the California fishing industry, drawing upon some of the most fertile renewable resources in the world, underwent massive, thoroughgoing modernization in the first quarter of this century, triggered by the mechanization of fishing and the coincident opening of worldwide markets to local fish processors. Public agencies charged with the oversight of the industry and the conservation of fishery resources made valiant efforts to keep pace with new problems thrust upon them by the sudden industrialization of fishing. Their failure to do so effectively illustrates in stark relief the nature of twentieth-century problems in the management of wildlife, air, water, and other shared resources in a competitive economy.