Organizations
- Central Imagery Office, a predecessor organization of the National Geospatial-Intelligence Agency (an American-government agency)
- Central Intelligence Organisation, the national intelligence agency of Zimbabwe
- Congress of Industrial Organizations, a former American trade union federation (also known as the Committee of Industrial Organization) that merged with the American Federation of Labor to form the AFL-CIO in 1955
- alternate acronym for the International Olympic Committee (French: Comité international olympique)
Read more about this topic: CIO