GCA
- GCA (gene)
- GCA Airlines
- GCA Games Convention Asia
- GCA Savvian
- Gahanna Christian Academy
- Garden Centers of America
- Garland Christian Academy
- Geelong Cricket Association
- Generalized Clifford algebra
- Geochimica et Cosmochimica Acta
- Georgia-Cumberland Academy
- Giant cell arteritis
- Giant-cell arteritis
- Global Center on Adaptation
- Global Communications Academy
- Goa Cricket Association
- Goodreads Choice Awards
- Gothenburg City Airport
- Government College of Architecture
- Government College, Ajmer
- Grace Christian Academy (Cayman Islands)
- Grand Canyon Association
- Grand Central Airport (United States)
- Grand China Air
- Granville Christian Academy
- Great Commission Association
- Greater Central Asia
- Greek Cypriot Administration of Southern Cyprus
- Greenbrier Christian Academy
- Greig City Academy
- Groceries Code Adjudicator
- Ground-controlled approach
- Gujarat Cricket Association
- Gun Control Act of 1968
- Gun Control Australia
- Guwahati College of Architecture
- The Great Canadian Appathon
- The Greeting Card Association