THE EUROPEAN UNION (EU) faced a stalemate of institutional reform between the signing of the Treaty of Nice in 2001 and the Treaty of Lisbon in 2009. Although the provisions of the Treaty of Nice were far from resolving the institutional troubles of the EU in the aftermath of the Eastern enlargement, the process for wider reform was painstaking and long. This book explains the convoluted process through which the EU managed to achieve the much-needed, but least expected institutional reform following the Nice Treaty. Thus the major puzzle, which the book tackles, is the dynamics under which the political actors changed their positions and preferences to agree on the Treaty of Lisbon provisions for further institutional reform. In other words, why did political actors shift their preferences in the aftermath of the Treaty of Nice? What were the reasons and processes that pushed the EU towards further reform?