IAA may refer to:
Businesses and organisations International organizations International Academy of Architecture International Academy of Astronautics International Actuarial Association International Advertising Association International Ammunition Association International Astrostatistics Association
Schools Idyllwild Arts Academy, in Idyllwild, California, US Interlochen Arts Academy of the Interlochen Arts Academy, in Miichigan, US Inter-American Academy of Guayaquil, in Ecuador International Academy Amman, a school in Jordan
Transportation organizations Indianapolis Airport Authority, in the US Irish Aviation Authority Israel Airports Authority
Other organizations Academia Sinica Institute of Astronomy and Astrophysics, in Taiwan Illinois Agricultural Association, now Illinois Farm Bureau, in the US Immigration Appellate Authority, in the UK Independent Ambulance Association, in England Indian Association of Alberta, in Canada Institute for Applied Autonomy, an activist group of anonymous artists Information Affairs Authority, in Bahrain Instituto Antártico Argentino ('Argentine Antarctic Institute') Instituto de Arqueología Amazónica ('Amazon Archaeology Institute'), in Peru Instituto de Astrofísica de Andalucía ('Institute of Astrophysics of Andalusia') Israel Antiquities Authority Israeli Astronomical Association
Science and technology Imidazoleacetic acid, a neurotransmitter metabolite Indole-3-acetic acid, a plant hormone Inflammatory aortic aneurysm, a medical condition Interrupted aortic arch, a heart defect Iodoacetamide, an alkylating agent for peptide mapping Isoamyl alcohol, a common name for 3-Methylbutan-1-ol
Transportation Igarka Airport, Russia, IATA code IAA Iran Aseman Airlines, an Iranian airline
Other uses Interactive Achievement Awards, now D.I.C.E. Awards, in the video game industry International Affairs Agency, a fictional entity in Grand Theft Auto V International Motor Show Germany, or Internationale Automobil-Ausstellung Islamic Army of Aden, or Aden-Abyan Islamic Army, a Sunni Islamist militant group in Yemen