ATC
- A Touch of Class (band)
- ATC (belay device)
- Academy for Technology and the Classics
- Adult Third Culture Kids
- Advanced Technology College
- Advanced transportation controller
- Against the Current (band)
- Agreement on Textiles and Clothing
- Aiken Technical College
- Air Tanzania Corporation
- Air Training Command
- Air Training Corps
- Air Transport Command
- Air traffic control
- Air traffic controller
- Alabang Town Center
- All Things Comedy
- All Things Considered
- All-terrain vehicle
- Altice (company)
- Alvarado Transportation Center
- Ambrose Treacy College
- American Technology Corporation
- American Thermoplastic Company
- American Tobacco Company
- American Tractor Corporation
- American Truck Company
- American Truck Corporation
- American-Turkish Council
- Anaplastic thyroid cancer
- Anatomical Therapeutic Chemical Classification System
- Ancillary Terrestrial Component
- Appalachian Trail Conservancy
- Applied Technology Council
- Aquarian Tabernacle Church
- Argentina Televisora Color
- Armacham Technology Corporation
- Armored Troop Carrier (LCM)
- Artist trading cards
- Athletic Trainer Certified
- Atlanta Track Club
- Atlanta Transit Company
- Auckland Theatre Company
- Audio Tele-Conference
- Australian Telecommunications Corporation
- Authorization to Carry
- Automatic and Track Control
- Automatic taxonomy construction
- Automatic tool changer
- Automatic train control
- Average total cost
- Fédération Internationale de l'Automobile
- Glossary of bets offered by UK bookmakers
- New Zealand Air Training Corps
- SV Atlétiko Tera Corá
- UK Astronomy Technology Centre
- USENIX Annual Technical Conference
- Utah College of Applied Technology