• African, Caribbean and Pacific countries that are signatories of the Cotonou Agreement

Organizations

• ACP Magazines, an Australian magazine publiser.
• Active Citizen Project, non-profit social change organization
• American College of Physicians, a national organization of doctors of internal medicine in the United States
• Associated Collegiate Press, a national membership organization for college student media in the United States
• Association of Contingency Planners, an international organization of professionals and those interested or involved with business continuity, disaster recovery or other related emergency or crisis management endeavors.
• Association of Chess Professionals, and organisation to protect professional chess players' rights and promote the game of chess

Science & technology

• Acepromazine, a sedative used commonly in veterinary medicine
• Acyl Carrier Protein, a fundamental protein in fatty acid and polyketide biosynthesis
• Admin Control Panel, a panel on forums and websites for editing setup (i.e. phpBB)
• Airlines Control Program, an operating system developed by IBM for processing airline reservations and related data
• Alan Cocconi Propulsion, a California electric vehicle drive systems company
• Algebra of Communicating Processes, an algebraic approach to reasoning about concurrent systems
• Automatic Cell Planning, a term used in mobile communications
• Average CPU Power, a power consumption metric proposed by Advanced Micro Devices

Other

• Acampe, an orchid genus
• Acid calcium phosphate, an ingredient in baking powder
• Address Confidentiality Program, a privacy service for victims of crime in the United States
• Advanced Care Paramedic, a diploma progam accredited by the Canadian Medical Association
• Aerospace Cadets of the Philippines, a youth program oriented in aerospace technology, whose aim is to promote national enthusiasm in the Philippines.
• Air Cadet Publication, a publication which describes a section of the Air Training Corps and is vital to the structure and smooth running of the organisation.
• Airport Core Programme, the construction project of Hong Kong International Airport and related in Hong Kong
• Alliance for Climate Protection
• Allied Communication Publication, a military protocol specification by the CCEB
• Aluminium Composite Panel, a material used mainly for building facades
• American Communist Party
• Application Communication Protocol, a vehicle telematics protocol created by Motorola
• Architects' Co-Partnership, prominent British architectural company
• Armenian Communist Party, a communist political party in Armenia
• Array Control Processor
• Associate Computing Professional, a certification offered by the Institute for the Certification of Computing Professionals
• Associated Construction Publications, a national network of regional publications that serve the construction industry. Owned by Reed Construction Data.
• Atmospheric Chemistry and Physics, a journal published by the European Geosciences Union
• Audax Club Parisien, organizer of the Paris-Brest-Paris grand randonnee, and worldwide sanctioning body for brevet (randonnee/audax) cycling events
• Australian Consolidated Press, a major publisher of magazines in Australia
• Automatic Colt Pistol, an ammunition standard
• Autoridad del Canal de Panamá (Panama Canal Authority), the authority in charge of the Panama Canal