Aia, a small town in the province of Gipuzkoa, Spain
Peñas de Aya, small mountain range in Oiartzun, Gipuzkoa
Aia, current Kutaisi, ancient capital of Colchis
Aia, another name for Aea (Malis), an ancient town in Greece
Aia, the collected edition of E. C. Vivian's 1920s novels Fields of Sleep and People of the Darkness
Saint Aia (died c. 711), Belgian Catholic saint also known as Aye
Academia
Abstract Intelligent Agent, a generalization and a hypothetical essence of human intelligence
Archaeological Institute of America
Arizona Interscholastic Association
Art Institute of Atlanta, a private fine-art college
Association for Industrial Archaeology, a body supporting the archaeology of industry in Britain
Artists' International Association
Statutes and treaties
Access to Information Act, a Canadian freedom of information act
Leahy-Smith America Invents Act
Anglo-Irish Agreement, a 1985 agreement between the governments of Ireland and the UK, aimed at bringing an end to The Troubles
Anti-Injunction Act, a US federal law
Aerospace
Aerospace Industries Association
American International Airways, now known as Kalitta Air
Avies, an Estonian airline (ICAO code: AIA)
Airports
Adelaide International Airport
Alliance Municipal Airport in Alliance, Nebraska (IATA Code: AIA)
Asuncion International Airport, in Luque, Asuncion, Paraguay
Athens International Airport, serving Athens, the Greek capital
Auckland Airport in Auckland, New Zealand
Sport and entertainment
Aliens in America, an American comedy TV show
Arizona Interscholastic Association, an Arizona high school athletics association
Asociación Iberoamericana de Atletismo, the governing body for the sport of athletics of European, Latin-American, and African countries with Iberian origin and/or Spanish or Portuguese language
Athletes in Action, an evangelical sports ministry
Autódromo Internacional do Algarve, a motor-racing track in Portugal
Business
American Insurance Association
AIA Group, a Hong Kong insurance and finance corporation
Amerindo Investment Advisors, a financial-services company
Annual investment allowance, a type of capital allowance in accounting
Technology and engineering
Application Integration Architecture, an integration framework marketed by Oracle Corporation
Atmospheric Imaging Assembly, an instrument that provides imaging of the Sun's corona on the Solar Dynamics Observatory
Automated Imaging Association
Authority Information Access
Automated immunoassay
Professional bodies and qualifications
Alliance of Independent Authors
American Institute of Architects
Associate of the Institute of Actuaries
Association of International Accountants
Australian Institute of Architects
Afghan Interim Administration
America's Infrastructure Alliance
Other
Anguilla, from its ISO 3-letter country code
Air Intelligence Agency, the former name of the Air Force Intelligence, Surveillance and Reconnaissance Agency of the United States