In striking contrast to the legislatures in most modern democracies, Congress retains an important place in American politics and policy making. Especially in recent years, this has led many observers to question the importance of the presidency and bureaucracy to the real work of American governance and the extent to which political actors in the executive branch generally exercise power. This narrative of congressional dominance has been particularly bolstered by recent scholarly interest in principal-agent models of interbranch relations. The assumption of congressional centrality, however, obscures many important features of American politics. Over the course of American history, institutional development in particular has often been driven by either autonomous executive action or conflicts between Congress and the executive. We develop an approach for assessing executive power in institutional politics and illustrate the logic of executive influence with three cases: the rise of federal food-and-drug and forestry regulation, and the growth of the federal farm extension service in the early twentieth century; the rise of the national security state in the mid-twentieth century; and the evolution of budgeting and spending practices over the course of the twentieth century.