| Acronym |
Agency/Organization/Definition |
| OAPEC |
Organization of Arab Petroleum Exporting Countries |
| OAS |
Organization of American States |
| OAU |
Organization of African Unity |
| 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 |
| OJP |
Office of Justice Programs |
| ONUB |
United Nations Operation in Burundi |
| ONUSAL |
United Nations Observer Mission in El Salvador |
| OPANAL |
Organismo para la Proscripcion de las Armas Nucleares en la America Latina y el Caribe; see Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean |
| OPCW |
Organization for the Prohibition of Chemical Weapons |
| OPEC |
Organization of Petroleum Exporting Countries |
| OMB |
Office of Management and Budget |
| OSCE |
Organization for Security and Cooperation in Europe |
| OSF |
Office of Space Flight (NASA) |
| OSHA |
Occupational Safety and Health Administration |
| OTA |
Office of Technology Assessment |
| OTS |
Office of Thrift Supervision |
