In recent decades, South East Asia has become one of the world's most popular destinations for foreign investment. The member states of the Association of Southeast Asian Nations (ASEAN) have employed varying modalities to pursue first security and then economic cooperation. This book explores regional law and governance in ASEAN through the lens of its regulation of foreign investment. It adopts a new framework to identify the unique ontological autonomy of the ASEAN Investment Regime beyond a simple aggregation of its individual member states. It deploys a sociology-led approach (especially constructivism) and emphasizes ideational factors (such as culture and norms) that guide state actions from within. The book explores the manner in which ASEAN's history and culture have fundamentally shaped its foreign investment policies, leading to outcomes that often depart fundamentally from the external structure and script of Global Investment Law.