IWC
- BirdWatch Ireland
- IAAF World Challenge
- Imperial War Cabinet
- Inch of water
- Independent Water Commission
- Industrial Water Cooling
- Industrial Welfare Commission
- Institute for Workers' Control
- International Grains Council
- International Watch Company
- International Water Centre
- International Whaling Commission
- International Wheelset Congress
- International Wolf Center
- International Wrestling Cartel
- Internet wrestling community
- Iowa Wesleyan College
- UIAA Ice Climbing World Cup