ALG may refer to:

• Advanced Landing Ground, temporary airfields created by the Allies in World War II
  • ALG Wormhout, the Advanced Landing Ground home base of 'B' Flight, 665 (AOP) Squadron RCAF, near Dunkirk, France
• Houari Boumediene Airport (IATA airport code ALG), Algiers, Algeria

• ALG, a company that provides information on future residual values of vehicles; purchased by TrueCar in 2011
• American Laser Games, a former US company
• Apple Leisure Group, a US travel company
• Association of London Government, a local government association in England
• Art. Lebedev Group, the holding company which owns Art. Lebedev Studio

• Anti-lymphocyte globulin, an immunosuppressive drug
• Application-level gateway, in computer networking

• A-League, a domestic football league in Australasia
• ALG Spor, a football club in Gaziantep, Turkey

• Algeria, IOC country code
• Algonquian languages (ISO 639 code ALG)
• Automatic Language Growth, an approach to language learning/teaching