The bureaucracy is the fourth branch of government, often receiving attention in times of emergency or when it is the object of criticism from the media or politicians. Less understood is how bureaucratic institutions function in a democracy, both from an organizational perspective and as institutional participants within the political arena. Drawing on rational choice approaches, computationally intensive data and modeling techniques, and systematic empirical inquiry, this original collection of essays highlights the important role bureaucracies play in shaping public policy-making. The editors of and contributors to this volume demonstrate not only the constraints political officials face in harnessing the bureaucracy but, more important, how bureaucracies function as organizational entities in diverse contexts. George A. Krause is Associate Professor of Political Science, University of South Carolina.