This doctoral research is about the EU and the ASEAN regarding with their developments of policy, politics and polity for transformation of different types of governance in their own way. The EU is regarded as the most successful regional integration project in the modern world because of its unique characteristics like Single Market, European Monetary Union (EMU), its single currency (Euro) and etc. Due to this sui generis character of the EU, some argued that there is no other possibly comparable instance of international integration in the global political scene. However, whether or not the EU is a motivating factor and admiring object for all other late comers of regional integration projects, it is undeniable that there are also relatively successful regional integration projects in the world outside the EU realm, for example, the ASEAN in Southeast Asia. It is also very interesting how heterogeneous members of the ASEAN manage to form a regional organization encompassing all countries in the region even though there is a great disparity of development and growth and also deep variances of own interests. At least the ASEAN can also be compared with the EU in the sense to explain why there is absence of war among member states by using both organizations as independent variable in terms of their economic, political and security cooperation. This study is a comparative analysis of different approaches to regional integration between the EU and the ASEAN as well as their changing modes of governance resulting from these approaches respectively. For the comprehensive understanding of politics and policy-making in the EU and the ASEAN, an analytical study of institutional designs, structures and organizational developments was carried out. Focus is to explain the major differences between the EU and the ASEAN and also to study internal factors and major processes, which determine the achievements, failures and stagnations of both organizations in the past decades. For analysis of policy-making and governance in the EU and the ASEAN, case studies on Common Foreign and Security Policy (CFSP) of the EU, Common Agricultural Policy (CAP) of the EU, ASEAN political and security cooperation, ASEAN Free Trade Area (AFTA) and ASEAN Economic Community (AEC) are conducted. It also examines the critical question whether the EU is in fact a system of governance with its own sui generis polity or whether it is just a useful instrument of its member states. Simultaneously, this study attempts to give a comprehensive view of the governance approach that has played an important role in the vitalization of regional integration studies in the recent years.