With closer regional integration there is increasing interest within the Association of Southeast Asian Nations (ASEAN) and on the part of the ASEAN’s dialogue partners in the potential gains of closer connections between Southeast Asia and South Asia. The strategic positions of India, Myanmar and Thailand provide the basis and scope for implementing multi-modal connectivity projects, for building upon and improving existing infrastructure and processes for cross-border connectivity in trade. With outward-looking policies in the various subregions that seek to link their economies closer than ever, the ASEAN and South Asian countries are presented with a wide array of options at the bilateral, subregional and regional levels that can be pursued in partnership under the different frameworks for cooperation. The role of regional entities such as the Asian Development Bank is also important to consider. This chapter assesses the political economy and other implications of cross-border connectivity between South and Southeast Asia, and suggests practicable options for moving forward.