With the adoption of the ASEAN Charter in 2008, the ASEAN member states articulated their vision of an economic community. This ambitious vision tracks economic reality around ASEAN. The ASEAN region has recently been one of the most popular destinations for FDI across the globe. Despite a temporary decline due to the COVID-19 pandemic in 2020, the region’s share of global FDI rose from 11.9 percent to 13.7 percent that year. Against this auspicious background, this book calls for a new framework through which we can conceptually embrace the ontological autonomy of the ASEAN Investment Regime (AIR), beyond an aggregation of the interests of its individual member states. A sociology-led approach, especially constructivism, emphasizes ideational factors, such as culture and norms, that guide state actions from within. The main goal of the book is to explore the manner in which ASEAN’s history and culture has fundamentally shaped its foreign investment policies, leading to outcomes that often depart from the external structure and script of Global Investment Law.