EU Federalism and Constitutionalism: The Legacy of Altiero Spinelli, edited by Andrew Glencross and Alexander H. Trechsel, represents the first book-length study of the travails of the implementation of federalism at the European level from the perspective of Altiero Spinelli’s ideas and his political life, which were both devoted to a federally united Europe. It is also a timely publication given the protracted struggle to implement a new EU institutional architecture-the 2009 Lisbon Treaty-that is already being tested by the fallout from the global financial crisis. This fallout has brought into stark relief the tensions within the EU over the question of enhancing solidarity and federal unity or remaining a looser association of sovereign states. Hence by examining the successes and failures of federalism within the EU system, the book seeks to explain not only how the EU has reached its current impasse but also how it may fare in the future. To achieve this objective, the book takes an interdisciplinary approach that covers all three dimensions of the European project: historical, legal, and political. In this fashion, Andrew Glencross and Alexander H. Trechsel’s EU Federalism and Constitutionalism: The Legacy of Altiero Spinelli offers a comprehensive and up-to-date analysis of the history, evolution, and future of federal principles and institutions in the European integration process.