Federalism is spreading around the world as a system of government, yet its origins as a political theory remain obscure. Modern federalism was first developed at the end of the eighteenth century. While Kant identified in federalism the value aspect of universal peace, Alexander Hamilton’s The Federalist Papers identified its main institutional features, commenting on the new federal American Constitution. This collection offers the first systematic comparison of Kant’s and Hamilton’s moral and political thought. The essays highlight the similarities and the differences between these two classics, as well as exploring their reception in different countries. The book focuses on their specific contributions to the development of federalism as a political theory, and touches on the contemporary significance of federalism with regard to issues such as peace, international order, and multinational and multicultural contexts. The combined analysis of Kant’s and Hamilton’s theories of peace, and of their institutional preferences, sheds light on present-day debates around peace and democracy. The book is a valuable contribution for scholars of federalism and of the writings of Kant and Hamilton.