The role in public policy of organizations—broadly defined to include bureaucratic and corporatist, as well as autonomous, organized interests—merits attention as a form of political participation characteristic of a wide variety of societies. Various forms of corporatism have emerged in recent years to play an increasingly important role in most West European societies. In Japan and the United States, organized interests are still mediated primarily by the political parties, but in these countries also there is an increasing reliance on organizational participation. Organized interests play an important role in contemporary authoritarian states, and provide a common denominator for comparisons with other political systems. Special cases of organizational participation that have received considerable attention include the role of the military as a form of bureaucratic politics in many countries, and the decision-making function of organizations in the international system. A better understanding of organizational participation as the most appropriate basis for the comparative study of contemporary political systems calls for further research along several lines: for example, the direct influence of organized interests on governments; the interaction of corporatist and autonomous organizations with bureaucracies; comparisons of organizational participation in societies with differing institutional heritages; and the role of organizations in the international system.