The world trading system is divided into an expanding succession of free and regional trade areas (RTA) whose implications for growth and convergence are still debated. While the European Union pursues its integration through deepening and widening, MERCOSUR and ASEAN continue their own economic integration. The rationale of regional integration is its expected impact on the prosperity and welfare of member countries. What are the gains and losses associated with membership to an RTA? Do regional unions promote convergence or divergence of income levels amongst member countries? Does regionalization impede or foster world welfare? This book provides one of the most complete evaluation of the impact of regional integration on economic development. Our research based on a synthesis between new growth and new geography theories indicates where, following the integration process, the creation (and destruction) of goods, services and capital will occur and how regional integration can encourage the transition towards economic convergence.