A theory may distort our understanding of historical phenomena for two reasons. Perhaps a perfectly sound theory has been misapplied in the particular instances. Alternatively, the failure of those who use the theory may reveal weaknesses in the theoretical structure itself. Pluralism has failed to explain McCarthyism, agrarian radicalism, and the relation between them. We will first review the evidence that refutes pluralist interpretations of these movements. We will then examine the defects in the general theory of pluralism that have contributed to its specific failures here.