After the war, the squadron returned home and was deactivated on 28 January 1946.
Early in 1946 a group of Marine aviators in the Washington, D.C. area began organizing a reserve fighting squadron from the ranks of pilots, officers, and enlisted members who had served together in the war as VMF-321.
This new VMF-321 became an organized Marine Corps Reserve fighting squadron in July 1946 at Naval Air Station Anacostia, Maryland, and was assigned 14 Corsair aircraft similar to the ones flown by the squadron during the war.

On April 1, 1949, Marine Fighting Squadron 321 was redesignated Marine Fighter Squadron 321.
The squadron was placed on alert January 13, 1951 and was activated on March 1, 1951 flying the F8F Bearcat during the Korean War.
The 164-man unit began an intensive training program under the command of Major George Robertshaw, in preparation for deployment to the Far East.

The squadron did not go to Korea as a unit.
Instead it was declared an augmentation squadron and its members were assigned to regular Marine units to fill empty billets.

In the 1950s, the squadron flew the A-1 Skyraider and on 15 May 1958 they were redesignated Marine Attack Squadron 321 (VMA-321).
In 1962, NAS Anacostia ceased fixed-wing flying operations and both it and adjacent Bolling AFB's runways closed due to airspace and traffic pattern conflicts with Washington National Airport.
 NAS Anacostia then became Naval Support Facility Anacostia with heliport operations only.
 At this point, all assigned USN and USMC flying units, to include VMA-321, relocated to nearby Andrews AFB, Maryland and the newly established Naval Air Facility Washington.
 On 1 July 1962, the squadron again became VMF-321 when it began flying the FJ-4B Fury.
This was followed by a transition to the F-8 Crusader in January 1965.

In October 1973.
a new paint scheme, consisting of a black dorsal and vertical stabilizer prompted a temporary nickname changed to the "Black Barons".
However, the squadron shortly returned to the "Hell's Angels" adding a pitchfork running through the " MG" on the vertical stabilizer.

Marine Fighter Squadron 321 was redesignated Marine Fighter Attack Squadron VMFA-321 in December 1973, when it became the first Marine Air Reserve squadron to receive the F-4 Phantom II aircraft.
The designation, which remains today, indicated the dual fighter/attack mission.
Aircrew and maintenance personnel began preparing for the new aircraft long before its arrival, and on January 15, 1974, VMFA-321 made its first Phantom flight.

Reservists from VMFA-321 appeared in a film produced for recruiting personnel into the Marine Corps Air Reserves.
The film, which featured actor and former Marine Christopher George, was produced in the summer of 1976 at Andrews Air Force Base by J. Walter Thompson, which has held the Marine Corps recruiting account contract for decades.

In 1985, VMFA-321 operated twelve F-4S Phantom aircraft and accumulated 12,344 mishap free hours.
During the calendar year the squadron flew nearly 3,000 hours in support of a demanding aircrew training program.
VMFA-321 was nominated for the Chief of Naval Operations Safety Award.
After the war, the squadron returned home and was deactivated on 28 January 1946. Early in 1946 a group of Marine aviators in the Washington, D.C. area began organizing a reserve fighting squadron from the ranks of pilots, officers, and enlisted members who had served together in the war as VMF-321. This new VMF-321 became an organized Marine Corps Reserve fighting squadron in July 1946 at Naval Air Station Anacostia, Maryland, and was assigned 14 Corsair aircraft similar to the ones flown by the squadron during the war.
On April 1, 1949, Marine Fighting Squadron 321 was redesignated Marine Fighter Squadron 321. The squadron was placed on alert January 13, 1951 and was activated on March 1, 1951 flying the F8F Bearcat during the Korean War. The 164-man unit began an intensive training program under the command of Major George Robertshaw, in preparation for deployment to the Far East.
The squadron did not go to Korea as a unit. Instead it was declared an augmentation squadron and its members were assigned to regular Marine units to fill empty billets.
In the 1950s, the squadron flew the A-1 Skyraider and on 15 May 1958 they were redesignated Marine Attack Squadron 321 (VMA-321). In 1962, NAS Anacostia ceased fixed-wing flying operations and both it and adjacent Bolling AFB's runways closed due to airspace and traffic pattern conflicts with Washington National Airport.  NAS Anacostia then became Naval Support Facility Anacostia with heliport operations only.  At this point, all assigned USN and USMC flying units, to include VMA-321, relocated to nearby Andrews AFB, Maryland and the newly established Naval Air Facility Washington.  On 1 July 1962, the squadron again became VMF-321 when it began flying the FJ-4B Fury. This was followed by a transition to the F-8 Crusader in January 1965.
In October 1973. a new paint scheme, consisting of a black dorsal and vertical stabilizer prompted a temporary nickname changed to the "Black Barons". However, the squadron shortly returned to the "Hell's Angels" adding a pitchfork running through the " MG" on the vertical stabilizer.
Marine Fighter Squadron 321 was redesignated Marine Fighter Attack Squadron VMFA-321 in December 1973, when it became the first Marine Air Reserve squadron to receive the F-4 Phantom II aircraft. The designation, which remains today, indicated the dual fighter/attack mission. Aircrew and maintenance personnel began preparing for the new aircraft long before its arrival, and on January 15, 1974, VMFA-321 made its first Phantom flight.
Reservists from VMFA-321 appeared in a film produced for recruiting personnel into the Marine Corps Air Reserves. The film, which featured actor and former Marine Christopher George, was produced in the summer of 1976 at Andrews Air Force Base by J. Walter Thompson, which has held the Marine Corps recruiting account contract for decades.
In 1985, VMFA-321 operated twelve F-4S Phantom aircraft and accumulated 12,344 mishap free hours. During the calendar year the squadron flew nearly 3,000 hours in support of a demanding aircrew training program. VMFA-321 was nominated for the Chief of Naval Operations Safety Award.
VMFA-321