ACW may refer to:
Military
- American Civil War
- Air Control Wing, e.g.:
- 116th Air Control Wing
- 461st Air Control Wing
- 552d Air Control Wing
Other
- Acorn Cambridge Workstation, a microcomputer
- Ancient Christian Writers, a book series
- Anticlockwise
- Arts Council of Wales
- Ashfield–Colborne–Wawanosh, a municipality in Ontario, Canada
- Assault Championship Wrestling
- ISO 639-3 code for Hejazi Arabic, a language dialect