| Abbreviation | Definition |
|---|---|
| IAS-USA | International Antiviral Society–USA |
| IATA | Illinois Athletic Trainers Association |
| IATA | International Air Transportation Association |
| IATAN | International Association of Travel Agents Network |
| IATE | International Association for Tourism Economics |
| IATEFL | International Association of Teachers of English as a Foreign Language |
| IAU | International Astronomical Union |
| IAVRT | International Association of Virtual Reality Technologies |
| IAW | International Association of Writers |
| IAWF | International Association of Wedding Florists |
| IAWF | International Association of Wildland Fire |
| IAWP | International Association of Wedding Planners |
| IAWP | International Association of Wedding Professionals |
| IAYT | International Association of Yoga Therapists |
| IAZ | Insurers Association of Zambia |
| IBAA | Insurance Brokers Association of Alberta |
| IBAM | Insurance Brokers Association of Manitoba |
| IBAT | Independent Bankers Association of Texas |
| IBBISBBFH | International Brotherhood of Boilermakers, Iron Ship Builders, Blacksmiths, Forgers, & Helpers |
| IBC | Insurance Bureau of Canada |