IAA

IAA may refer to:

Terminology

 * Indole-3-acetic acid, a plant hormone
 * Aux/IAA repressors, a class of early auxin responsive transcription factors in plants
 * Insulin autoantibody, used in diagnosing Latent autoimmune diabetes
 * Interrupted aortic arch, a medical condition
 * Iodoacetamide, an alkylating agent
 * Isoamyl alcohol, a common name for 3-Methylbutan-1-ol

Institutions & associations

 * Academia Sinica Institute of Astronomy and Astrophysics, a research institute in Taiwan
 * Instituto Antártico Argentino, Argentine Antarctic Institute: federal agency for Antarctic research
 * Instituto de Arqueología Amazónica, archeological research institute in Peru
 * Instituto de Astrofísica de Andalucía (IAA-CSIC), research institute in Spain
 * International Academy of Architecture, Bulgarian NGO & NPO
 * International Academy of Astronautics, Swedish NGO
 * International Actuarial Association, worldwide association of actuarial associations
 * International Astrostatistics Association
 * Israel Antiquities Authority, Israeli governmental authority
 * Israeli Astronomical Association

Aviation

 * Igarka Airport IATA code
 * Indianapolis Airport Authority
 * Iran Aseman Airlines, an Iranian airline
 * Irish Aviation Authority
 * Israel Airports Authority
 * International Academy of Astronautics

Automobile

 * International Motor Show Germany, known natively as Internationale Automobil-Ausstellung

Computing

 * Interactive Achievement Awards, now known as D.I.C.E. Awards

Education

 * Idyllwild Arts Academy, a private high school in Idyllwild, California
 * Intercollegiate Athletic Association, former name of the National Collegiate Athletic Association
 * Interlochen Arts Academy, a boarding school at the Interlochen Center for the Arts
 * Inter-American Academy of Guayaquil, an international school in Ecuador

Politics

 * Information Affairs Authority of Bahrain

Sports

 * International Ammunition Association

Associations (non-science-related)

 * Illinois Agricultural Association
 * Immigration Appellate Authority (UK)
 * Independent Ambulance Association representing private ambulance services in the UK
 * Indian Association of Alberta
 * Institute for Applied Autonomy
 * International Advertising Association, international marketing industry association
 * International Association of Art
 * Investment Adviser Association

Other uses

 * Id al Adha, Muslim holiday
 * Intelligence Authorization Act (1991 - U.S.)
 * Islamic Army of Aden, militant group designated as a terrorist organization by Bahrain, Canada and the UK