Government agencies service interest groups, advocate policies, provide advice to elected officials, and create and implement public policy. Scholars have advanced theories to explain the role of agencies in American politics, but efforts to test these theories are hampered by the inability to systematically measure agency preferences. We present a method for measuring agency ideology that yields ideal point estimates of individual bureaucrats and agencies that are directly comparable with those of other political actors. These estimates produce insights into the nature of the bureaucratic state and provide traction on a host of questions about American politics. We discuss what these estimates reveal about the political environment of bureaucracy and their potential for testing theories of political institutions. We demonstrate their utility by testing key propositions from Gailmard and Patty's (2007) influential model of political control and endogenous expertise development.