ACG may refer to:
- A codon of threonine in genome expression
- Academic Colleges Group, a New Zealand Educational Company
- Academic Competitiveness Grant, an assistance grant for college students in the USA
- Acocks Green railway station, in the United Kingdom, from its National Railway code
- The Air Combat Group RAAF of the Royal Australian Air Force
- Alternating current electrical generator
- American College for Girls, now called Robert College, of Istanbul
- American College of Gastroenterology
- American College of Greece
- American Comics Group, a comic-book publisher in the Golden Age of comic books
- Angle closure glaucoma
- Association for Corporate Growth
- Ashby Computers & Graphics, video game developer trading as Ultimate Play the Game
- Associated Carrier Group, a US industry association of CDMA cellular network operators
- Azeri-Chirag-Guneshli, an oilfield in the Caspian Sea