OAPEC: Organization of Arab Petroleum Exporting Countries
OAS: Organization of American States
OAU: Organization of African Unity; see African Union
ODA: official development assistance
OECD: Organization for Economic Cooperation and Development
OECS: Organization of Eastern Caribbean States
OHCHR: Office of the United Nations High Commissioner for Human Rights
OIC: Organization of the Islamic Conference
OIF: International Organization of the French-speaking World
ONUB: United Nations Operation in Burundi