ACS

ACS is a three-letter abbreviation with multiple meanings:

• ACS International Schools, formerly American Community Schools, a group of schools in southern England
• Action Code Script, a scripting language used in video games such as HeXen and modern Doom ports
• Actividades de Construcción y Servicios, S.A. (IBEX-35 stock symbol: ACS) (Madrid, Spain)
• Acute coronary syndrome (see angina), also known as "unstable angina", a form of chest pain due to reduced oxygen supply to the heart muscle
• Adaptive Comfort Standard, unofficial name for Standard 55 published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers
• Administration for Children's Services
• Administrative command system
• Advanced Camera for Surveys, an instrument aboard the Hubble Space Telescope
• Advanced Computing Systems
• Advantage Consulting Services, Inc. (Search Engine Marketing Firm)
• Aerial Common Sensor, a reconnaissance aircraft airframe developed by Lockheed Martin
• Affiliated Computer Services (stock symbol: ACS), an American information technology and business process outsourcing company
• African Cooperative Society
• Agency Computer Systems
• Air Cess (Liberia)
• Aircraft Combat Survivability
• Al's Circuit Simulator
• "Alaska Communications System", former name of AT&T Alascom, an American communications services company
• Alaska Communications Systems, an American communications services company, distinct from "AT&T Alascom"
• "Alternative Community School", former name of Lehman Alternative Community School of Ithaca, New York, United States
• Alternative Compensation System
• American Camellia Society
• American Canal Society
• American Cancer Society, an American medical organization
• American Cannabis Society
• American Carbon Society
• American Carousel Society
• American Ceramic Society
• American Cetacean Society
• American Cheese Society
• American Chemical Society, an American professional association
• American Clematis Society
• American Cockatiel Society
• American College of Sofia, a Bulgarian secondary school founded in 1860, at which English iss the primary language of instruction and American pedagogical methods are used
• American College of Surgeons
• American Colonization Society
• American Community Schools of Athens, a Greek private school using an American curriculum and mostly American-trained educators
• American Community Survey, a project of the U.S. Census Bureau
• American Conifer Society
• American Constitution Society for Law and Policy, or simply "American Constitution Society", an American non-profit educational organization
• American Cryonics Society
• Anchorage Christian Schools
• Anglo-Chinese school, Klang
• Anglo-Chinese School, Singapore
• Apolyton Civilization Site
• Applied Computer Sciences Inc.
• Army Community Service (US)
• Associated Colleges of the South (US)
• Association for Canadian Studies
• Association of Caribbean States
• Association of Cricket Statisticians and Historians
• Asymmetric Cooling System
• Assumption College School
• Australian Cinematographers Society
• Australian Computer Society
• Australian Correspondence Schools
• Australian Customs Service
• Automobil Club der Schweiz
• Auxiliary Crane Ship (US Navy hull classification symbol)