Understanding federalism - the form of political organization that unites separate polities within an overarching political system so that all maintain their political integrity - is central to the study of democratic government in the United States. Yet textbooks tend to cover the topic as a set of abstract principles or a maze of budgetary transfers with little connection to real political life. This concise and engaging text boils the discussion down to its essence: federalism is about power, specifically the tug for power among and within the various levels of government. Author Larry N. Gerston examines the historical and philosophical underpinnings of federalism; the various "change events" that have been involved in defining America's unique set of federal principles over time; and the vertical, horizontal, and international dimensions of federalism in the United States today. The result is a book with wide application for undergraduate students in American government, state and local politics, public administration, or any course examining the ways in which institutional political power is both diffused and concentrated in the United States.