IAF
- Fraunhofer Institute for Applied Solid State Physics
- Indian Air Force
- Indian Armed Forces
- Indonesian Air Force
- Industrial Areas Foundation
- Initial approach fix
- Intangible asset finance
- Integrate-and-fire
- Integrated Architecture Framework
- Inter-American Foundation
- International Abolitionist Federation
- International Accreditation Forum
- International Aikido Federation
- International Apostolic Fellowship
- International Astronautical Federation
- International of Anarchist Federations
- Iowa Atheists and Freethinkers
- Iraqi Accord Front
- Iraqi Air Force
- Islamic Action Front
- Islamic Republic of Iran Air Force
- Israel Allies Foundation
- Israeli Air Force
- Italian Air Force