This book analyzes the economic performance of the EU in the first five years after its largest expansion in 2004. Accession and integration were expected to foster growth and convergence among the new Member States through intensified trade, foreign direct investment, financial deepening and the adoption of the EU's institutional framework. With the benefit of five years experience, this book brings together experts from academia and think-tanks to assess the driving forces of economic growth and real convergence. The question whether the EU has made a difference in terms of growth is studied thoroughly from various angles, including that of country-specific and sector-specific analysis. It is shown that while the enlargement has been a success story overall, growth and catching-up cannot be taken for granted and the importance of economic policy remains undiminished.