IAB may refer to:
- Institute of Advanced Burnouts, (IAB) A non profit organisation specialising in research and development of safer methods to produce a controlled loss of traction in any vehicle or object with wheels
- Internal affairs (law enforcement) (Internal Affairs Bureau)
- Internet Architecture Board, committee charged with oversight of the technical and engineering development of the Internet by the Internet Society
- McConnell Air Force Base, Wichita, Kansas, United States, IATA airport code
- Individual Address Block (computers and computer networking)
- Infantry Assault Badge, German war badge awarded to Waffen SS and Wehrmacht Heer soldiers during WWII
- International Association of Book-keepers, a professional organization for bookkeepers
- International Association of Bryologists, a professional organization for bryologists
- Interactive Advertising Bureau, advertising business organization that develops industry standards, conducts research, and provides legal support for the online advertising industry
- Internet Advertising Bureau, a global collection of trade associations for digital advertising
- International Accounting Bulletin, an UK accounting publication focusing on global issues