Testing Theories of American Politics: Elites, Interest Groups, and Average Citizens Martin Gilens and Benjamin I. Page Each of four theoretical traditions in the study of American politics—which can be characterized as theories of Majoritarian Electoral Democracy, Economic-Elite Domination, and two types of interest-group pluralism, Majoritarian Pluralism and Biased Pluralism—offers different predictions about which sets of actors have how much influence over public policy: average citizens; economic elites; and organized interest groups, mass-based or business-oriented. A great deal of empirical research speaks to the policy influence of one or another set of actors, but until recently it has not been possible to test these contrasting theoretical predictions against each other within a single statistical model. We report on an effort to do so, using a unique data set that includes measures of the key variables for 1,779 policy issues. Multivariate analysis indicates that economic elites and organized groups representing business interests have substantial independent impacts on U.S. government policy, while average citizens and mass-based interest groups have little or no independent influence. The results provide substantial support for theories of Economic-Elite Domination and for theories of Biased Pluralism, but not for theories of Majoritarian Electoral Democracy or Majoritarian Pluralism. W ho governs? Who really rules? To what extent is the broad body of U.S. citizens sovereign, semi- sovereign, or largely powerless? These questions have animated much important work in the study of American politics. While this body of research is rich and variegated, it can loosely be divided into four families of theories: Majoritarian Electoral Democracy, Economic-Elite Domination, and two types of interest-group pluralism—Majoritarian Pluralism, in which the interests of all citizens are more or less equally represented, and Biased Pluralism, in which corporations, business associations, and professional groups predominate. Each of these perspectives makes different predictions about the independent influence upon U.S. policy making of four sets of actors: the Average Citizen or “median voter, ” Economic Elites, and Mass-based or Business-oriented Interest Groups or industries. Each of these theoretical traditions has given rise to a large body of literature. Each is supported by a great deal of empirical evidence—some of it quantitative, some historical, some observational —concerning the importance of various sets of actors (or, all too often, a single set of actors) in U.S. policy making. This literature has made important contributions to our understanding of how American politics works and has helped illuminate how democratic or undemocratic (in various senses) our policy making process actually is. Until very recently, however, it has been impossible to test the differing predictions of these theories against each other within a single statistical model that permits one to analyze the independent effects of each set of actors upon policy outcomes. Here—in a tentative and preliminary way—we offer such a test, bringing a unique data set to bear on the problem. Our measures are far from perfect, but we hope that this first step A permanent link to supplementary materials provided by the authors precedes the References section. Martin Gilens is Professor of Politics at Princeton University (mgilens@princeton.edu). His research examines representa- tion, public opinion, and mass media, especially in relation to inequality and public policy. Professor Gilens is the author of Affluence & Influence: Economic Inequality and Political Power in America (2012, Princeton University Press). Benjamin I. Page is Gordon S. Fulcher Professor of Decision Making at Northwestern University (b-page@- northwestern.edu). His research interests include public opinion, policy making, the mass media, and U.S. foreign policy. He is currently engaged in a large collaborative project to study Economically Successful Americans and the Common Good. For helpful comments the authors are indebted to Larry Bartels and Jeff Isaac, to the anonymous reviewers from Perspectives on Politics, and to seminar participants at Harvard University and the University of Rochester. 564 Perspectives on Politics doi:10.1017/S1537592714001595 © American Political Science Association 2014 Articles