| Abbreviation | Definition |
|---|---|
| IODR | Indian Ocean Disaster Relief |
| IODR | International Organization for Diplomatic Relations |
| IOE | IFORS (International Federation of Operational Research Societies) Online Encyclopedia |
| IOF | International Osteoporosis Foundation |
| IOH | Institute for Organizational Health |
| IOM3 | Institute of Materials, Minerals and Mining |
| IOOF | International Order of Odd Fellows |
| IP | India Partners |
| IPA | International Polychaetology Association |
| IPAM | Institute For Pure Applied Mathematics |
| IPAS | International Project Assistance Services |
| IPB | International Peace Bureau |
| IPBD | Illinois Partnership for Business Development |
| IPCA | Indiana Marketers and Convenience Store Association |
| IPCA | International Prison Chaplains Association |
| IPCR | Institute for Prostate Cancer Research |
| IPDRO | Internet Protocol Detail Record Organization |
| IPEMED | Institut de Prospective Economique du Monde Méditerranéen |
| IPEN | Instituto Peruano de Energía Nuclear |
| IPEN | International Physical activity and the Environment Network |