The rapid proliferation of free trade agreements (FTAs) is remarkable given the abundant scepticism about their economic benefits. Policy diffusion models offer the key to this puzzle since they highlight how these different sets of preferential trade agreements are interconnected (either because they generate externalities on non-members or because they disseminate novel policy paradigms), thereby underscoring the impact of peer pressure on FTA dissemination. The book also offers a sophisticated understanding of the drivers behind FTA proliferation, beyond traditional economic arguments, to encompass international political rivalry and the race to shape international trade rules. In so doing, it addresses the fundamental question as to how FTAs affect the regional integration process itself. FTAs can work for or against emergence of coherent regional blocs, and this book explores which conditions favor one outcome over the other.