IAG may mean:
- IAG – The IATA code for Niagara Falls International Airport
- Identity and Access Governance in computer security
- IAg – Immersion Silver plating, a conductor plating technology used for Printed circuit boards
- International Adventure Group, a group of individuals dedicated to international adventures
- International Airlines Group, holding company of British Airways and Iberia
- Louvain School of Management – Institut d'Administration et de Gestion
- Idiopathic adolescent gynecomastia, a medical condition
- Iraq Assistance Group
- Investment Analysis Group at the Leonard N. Stern School of Business, New York University
- Information, Advice and Guidance
- The Information Architecture Group
- Insurance Australia Group, an insurance company in Australia
- It's A Goal, an online football management simulator
- International Audio Group, a manufacturer of hi-fi equipment
- Informal Agenda Group
- International Association of Geodesy, one of seven associations within the International Union of Geodesy and Geophysics (IUGG)
- International Association of Geomorphologists (IAG/AIG)
- Microsoft Intelligent Application Gateway, a combined hardware and software computer product by Microsoft
- I Am Ghost, a post-hardcore band from Long Beach, California
- Drew Carey's Improv-A-Ganza