This publication analyses how closer regional connectivity and economic integration between South Asia and Southeast Asia can benefit both regions. With a focus on the role played by infrastructure and public policies in facilitating this process, it provides a detailed and up-to-date discussion of issues, innovations, and progress. Country studies of national connectivity issues and policies cover Bangladesh, India, Myanmar, Nepal, Sri Lanka, and Thailand, examining major developments in trade and investment, economic cooperation, the role of economic corridors, and regional cooperation initiatives. Thematic chapters explore investment in land and sea transport infrastructure, trade facilitation, infrastructure investment financing, supporting national and regional policies, and model-based estimates of the benefits of integration. They also identify significant opportunities for strengthening these integration efforts as a result of the recent opening up of Myanmar in political, economic, and financial terms. For the first time for these regions, the book employs a state-of-the-art computable general equilibrium (CGE) model incorporating heterogeneous firms to estimate the advantages of integration.