Charitable Trust, a UK charity Anglican Church in Thailand The Association of Commercial Television in Europe, a group which represents the business interests of the commercial television sector at the EU institutions Associated Container Transport (ACT) a consortium of five British shipping companies - Ben Line, Blue Star Line, Cunard (Port Line), Ellerman Lines and the Harrison Line Law Act (document), a document recording the legality of a transaction or contract Acting (law) refers to someone temporarily exercising the powers of a vacant position Act of Parliament, Act of Congress, or Act of Tynwald, a statute or law passed by a legislature Advance corporation tax, a tax collected in the UK until 1999 Places Australian Capital Territory, the territory in which the Australian capital city of Canberra is seated Transport ACT, the IATA code for Waco Regional Airport, Texas, US ACT, the National Rail code for Ascot railway station, Berkshire, UK Science, technology, and mathematics Computing ACT-R, a symbolic cognitive architecture Apple Certified Trainer, one of the Apple certification programs ACT (NASDAQ), Automated Confirmation of Transactions, a trade reporting and clearing system Act! CRM, Contact Management and CRM software Medicine Acceptance and commitment therapy, a type of cognitive-behavioral therapy Acetylcholine, (ACt/ACh) a neurotransmitter Activated clotting time Adoptive cell transfer, transfer of cells into a patient, usually immune system cells Artemisinin based combination therapy, a treatment for malaria Assertive community treatment, a system for treating mental illness Other uses in science, technology, and mathematics Act or S-act, the action of a monoid on a set, or a semiautomaton ACT (audio format), a file format Ford ACT, a transit system Astrographic Catalog/Tycho or Tycho-2 Catalogue Atacama Cosmology Telescope, Chile ACT, a codon for the amino acid Threonine Other uses ACT mouthwash, produced by Chattem Acting (rank), temporary military rank Achterhooks, ISO 639-3 language code, a Dutch dialect Courtney Act, Australian drag queen, singer, and television personality