Regional organizations (ROs) are international organizations (IOs) whose membership is limited to states within a single geographic region. They have been established to foster cooperation and political and economic integration or dialogue among states within a region. They vary from loose cooperation arrangements to formal regional integration.^[1] Since their formal emergence after the end of World War II, they have become increasingly numerous and influential, often working closely with other multilateral organizations such as the United Nations.^[2]

Examples of ROs include, amongst others, the African Union (AU), Association of Southeast Asian Nations (ASEAN), Arab League (AL), Arab Maghreb Union (AMU), Caribbean Community (CARICOM), Council of Europe (CoE), Eurasian Economic Union (EAEU), European Political Community (EPC), European Union (EU), South Asian Association for Regional Cooperation (SAARC), Shanghai Cooperation Organisation, Asian-African Legal Consultative Organization (AALCO), Union for the Mediterranean (UfM), Union of South American Nations (USAN).

• International organization
• List of intergovernmental organizations
• List of regional organizations by population
• List of trade blocs
• Regional Economic Communities
• Regional integration
• Supranational union

• Tanja A. Börzel and Thomas Risse (2016), The Oxford Handbook of Comparative Regionalism. Oxford: Oxford University Press.
• Rodrigo Tavares (2009), Regional Security: The Capacity of International Organizations. London and New York: Routledge.