Human beings cannot survive lonely, but they need to be associated with each other in the society both locally and globally. Likewise, countries in the world cannot stand alone in the world, but the need to join hand in hand with others to move forward together. Therefore, many countries in all parts of the world have been cooperated as a group to jointly operate their economy, polity, and etc. The countries in the Southeast Asia is not the exception, they have established an association and developed as ASEAN for more than four decades. It is interesting to learn how the ASEAN has been organized and what its effects, both advantages and disadvantages, are.The Association of Southeast Asian Nations or ASEAN was established on 8 August 1967 in Bangkok, Thailand. It is a regionally international organization with the purpose to promote the cooperation, political stability, trade and economic growth, and social development of the member countries in southeastern Asia. Initially, ASEAN is consisted of 5 countries, namely Indonesia, Malaysia, the Philippines, Singapore and Thailand. After the cold war era, ASEAN has 5 more member countries so the total members are 10 countries. The 5 additional countries are Myanma, Brunei, Vietnam, Laos and Combodia.