In a properly-functioning democracy, public opinion should not only be correlated with, but also a major determinant of, public policy. Is that the case in the United States? In this chapter, we address that question by covering the major lines of empirical research on the relationship between American public opinion and public policy. We begin with early work that emphasized the limits of popular thinking about government, creating the apparent need for democratic elitism in governmental action. More recent literature includes perspectives from the public policy field, and research on democratic responsiveness at both the national and state levels. Major lines of work emphasize the existence of rational public opinion at the aggregate level which ‘smooths out’ the inconsistencies that may exist within individual policy attitudes. Seminal studies have considered both the degree of correspondence between opinion and policy (i.e., ‘the rational public’), and models that specify how policy responds to opinion (thermostatic responses and the macropolity). Recent methodological innovations have led to new insights about democratic responsiveness in the American states. Our general conclusion is cautiously optimistic: Policy generally does follow the contours of citizen preference, but elites also have opportunities to shape manifestations of public opinion.