Organizations
- Immaculate Conception Academy (Davenport, Iowa), USA, former Catholic girls high school
- Immaculate Conception Academy-Greenhills, an elite private all-girls Chinese school in Greenhills, San Juan, Metro Manila, Philippines. (Not to be confused with ICA Manila (ICAM) or ICA Dasmariñas)
- Immigration and Checkpoints Authority, a Singaporean authority for immigration and checkpoints
- Indoor Cricket Australia, the governing body of the sport of indoor cricket in Australia
- Institute of Combinatorics and its Applications, an international scientific organization based in Winnipeg, Canada
- Institute of Cultural Affairs, an international non-profit organisation
- Intercontinental A, a kart racing class for top drivers aged 15 and up
- Intercontinental Assembly
- International Clarinet Association
- Intermuseum Conservation Association
- International Cartographic Association
- International Christian Academy (Côte d'Ivoire), an American boarding school in Bouaké, Côte d'Ivoire.
- International Chiropractor's Association
- International Congress of Actuaries
- International Congress of Americanists
- International Co-operative Alliance, the worldwide umbrella body for co-operatives.
- International Commission for Acoustics
- International Communication Association
- International Contract Agency, the fictional organisation responsible for arranging hits for 47 in the Hitman series of games
- International Council on Archives
- Iranian Corrosion Association, an Iranian organisation whose aim is to update the public knowledge of corrosion and its prevention in industrial and urban facilities
- Irish Citizen Army, an organisation which lasted up to 1916 to rid Ireland of British rule and protect workers
- Irish Countrywomen's Association
- Irish Cycling Association
- Jewish Colonization Association Yiddish acronym
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