GCA may refer to:
- Games Convention Asia - A Video Games and interactive technology convention held annually in Singapore consisting of a public exhibition and a professional conference.
- Garden Centers of America - a nonprofit organization of independently-owned garden centers since 1973
- GCA (file format) - a compressed archive file format
- GCA (gene), a human gene
- Generalized Clifford algebra - an algebra in mathematics
- Geochimica et Cosmochimica Acta - a scientific journal specialising in geochemistry, cosmochemistry, and meteoritics.
- Georgia-Cumberland Academy - a Seventh-day Adventist private high school in the U.S. state of Georgia
- Giant cell arteritis, a form of vasculitis also known as temporal arteritis
- Global Cybersecurity Agenda - A framework for international cooperation in cybersecurity
- Gothenburg City Airport - a city airport in western Sweden
- Government College of Architecture in Lucknow, India
- Grand Central Airport (United States) - a former airport in Glendale, California
- Great Commission Association - an association of evangelical Christian churches
- Ground-controlled approach - A precision ground-radar based aircraft guiding procedure for landing in marginal weather conditions.
- Gun Control Act of 1968
- Gun Control Australia