ISB
- Benazir Bhutto International Airport
- Cummins B Series engine
- I Shalt Become
- Impact Statement for Business
- Imperial Security Bureau
- Independent sideband
- Indian School of Business
- Institute for Systems Biology
- Instituto Simón Bolívar
- International School Bangkok
- International School Basel
- International School Benghazi
- International School Brunei
- International School of Beaverton
- International School of Beijing
- International School of Belgrade
- International School of Bergen
- International School of Boston
- International School of Brno
- International School of Brussels
- International School of Bucharest
- International School of Business (Vietnam)
- International Socialist Bureau
- International Society for Biocuration
- International Society of Bassists
- International Society of Biomechanics
- International Staff Band
- International Submarine Band
- Islamabad International Airport
- Islamic Society of Baltimore
- Islamic Society of Boston
- Islamic Society of Britain
- National Park Service Investigative Services Branch
- The Incredible String Band