Industrial organization is as old as economics. Many of the best-remembered parts of the Wealth of Nations concern the central subject matter of the field: the effects of monopoly and collusion, the determinants of the size and structure of firms, and so forth. Much contemporary analytical work in the field remains energized by Cournot's contribution of over 150 years ago. However, the field did not flourish as a recognizable specialty in American universities until the 1930s. For much of the period since then, the work of American industrial organization economists was heavily colored by public policy issues. The question, sometimes explicit but almost always lurking close to the surface of this research, was "Big business: is it good or bad?" In part, this question was stimulated by the predilection for competition and the suspicion of monopoly and cooperation among sellers that marked the development of Anglo-Saxon economics. Peculiarly American concerns also helped shape this research agenda. The antitrust laws provide the obvious example, and much early work in the field was explicitly responsive to the policy issues arising from this American legal innovation. Antitrust was, however, only one manifestation of a deep populist strain running through American political history. And populist suspicions about the utility of large business organization provided a stimulus to early industrial organization research. It is accordingly no accident that the field should have grown to