4th CAG was the first civil affairs group in the Marine Corps and mostly supports II MEF.

On November 1, 1955, 4th CAG was activated originally as 5th Staff Group at Henderson Hall, Arlington, Virginia.

[6][7] During Operation Desert Storm, 4th CAG was assigned to 2nd Marine Division and helped process over 10,000 Iraqi POWs.

4th CAG sent a detachment to support Joint Task Force Katrina in New Orleans, Louisiana, from September to October 2005.

On December 15, 2013, 4th CAG was reactivated and relocated to Hialeah, Florida, as part of the Force Structure Review.