ACEC may refer to:
- Advisory Committee on Electromagnetic Compatibility, a branch of the International Electrotechnical Commission
- American Council of Engineering Companies, a representative of America's engineering industry
- Association of Consulting Engineering Companies (Canada), a not-for profit organization representing Canadian consulting engineering companies
Area of Critical Environmental Concern, a program managed by the Bureau of Land Management
- Area of Critical Environmental Concern (Massachusetts), a state level land protection program in Massachusetts.
- Australian Computers in Education Conference, a conference held by the Australian Council for Computers in Education every two years
- SA Ateliers de Constructions Electriques de Charleroi, Belgian electrical engineering company founded in 1904, defunct 1989