'The historical and geographical sweep of The Logic of Regional Integration is very impressive - ranging from the nineteenth-century German Zollverein to the contemporary European Union to Mercosur and beyond. But Mattli's finest achievement is coupling this empirical depth with a rigorous, parsimonious and persuasive thesis. His central argument that economic disparities between insiders and outsiders drive regional integration is a major contribution to the debate about this important phenomenon.' Geoffrey Garrett, Yale University