This chapter focuses on different groups of people who play a role in tax politics. One of the most important underlying dynamics of tax politics is the variety in levels of intensity that different groups bring to the issue. Income tax, in particular, has become the conduit through which nearly all federal social and economic policies are attempted, be it by libertarian Republicans or by liberal Democrats. The chapter discusses the high-intensity people in tax politics, who are either the special pleaders or the would-be populists. The special pleaders are mostly corporations and industry groups. The would-be populists, more central to the debates of fundamental reform, have grown adept at channeling the low-intensity resentment of the public at having to pay taxes into high-intensity legislative campaigns that seek to reshape not only the tax code but the place of government in American life.