The proliferation of preferential trade agreements (PTAs) is the most prominent and prevalent driver of regional trade governance in the contemporary international economy. PTAs grant member states preferential access to each other’s markets, and they also shape the contours of economic regionalism across different geographic neighborhoods. The chapter analyzes the central issues animating scholarship on regional trade governance, with a focus on the role of PTAs and the future research trajectories relevant to the evolution of regional institution-building. It examines the domestic and international political factors that influence the establishment, design, and the political as well as economic effects of PTAs. It also addresses how the budding “mega-PTAs” currently under negotiation may affect the stability and governance of the multilateral trading system. The analysis highlights an important research frontier in the study of PTAs: the emergence of deep integration agreements that seek extensive “behind-the-border” trade liberalization and regulatory coordination.