CAG or cag may refer to:

• Cagoule, a lightweight weatherproof raincoat or anorak with a hood.
• CAG promoter, used in molecular biology
• CAG, a codon for the amino acid glutamine
• Cagliari–Elmas Airport (IATA airport code: CAG) in Cagliari, Sardinia, Italy
• Canadian Association of Geographers
• Chassis Air Guide, in computers is Intel's thermal solution to PC chassis
• Cheap Ass Gamer, an online BBS community
• China National Aviation Corporation (ICAO airline designator: CAG)
• Chinese Academy of Governance, a training center for middle and senior government officials of the Chinese government
• Civil Affairs Group, an acronym for United States Marine Corps Civil Affairs Groups
• Closed angle glaucoma, a type of eye disease.
• Colegio Americano de Guatemala (American School of Guatemala)
• Combat Applications Group, an abbreviation of the former official name of Delta Force, a United States Army Special Operations Command military unit
• Commander, Air Group, the informal name for the senior US Navy officer of a carrier air wing
• Commentaria in Aristotelem Graeca, a series of original-language texts of ancient and Byzantine commentaries on Aristotle
• Communication Arts Guild, an organisation dedicated to the Indian advertising industry.
• Comptroller and Auditor General, a senior civil servant charged with improving government accountability.
• Computer-assisted gaming, used for example for PnP role-playing games
• ConAgra Foods Inc., stock ticker on New York Stock Exchange
• Consensus audit guidelines, a set of twenty security controls for cyber defense published by the SANS Institute
• Consumer Action Group, a UK forum which provides free help and support on consumer issues.
• Coronary angiography, a technique to visualize the arteries of the heart muscle
• Craig–Moffat Airport (FAA airport code: CAG) in Craig, Colorado, United States
• Nivaclé language (ISO 639-3 code), a language spoken in Paraguay and Argentina