The 3rd Marine Division is a division of the United States Marine Corps based at Camp Courtney, Marine Corps Base Camp Smedley D. Butler in Okinawa, Japan. It is one of three active duty infantry divisions in the Marine Corps and together with the 1st Marine Aircraft Wing (1stMAW) and the 3rd Marine Logistics Group forms the III Marine Expeditionary Force. The division was first formed during World War II and saw four years of continuous combat in the Vietnam War. Today, elements of the 3rd Marine Division are continuously forward deployed and forward postured to carry out the US Government's mission of a Free and Open Indo-Pacific in conjunction with its sister services.

Marine Light Attack Helicopter Squadron 267 (HMLA-267) is a United States Marine Corps helicopter squadron consisting of Bell AH-1Z Viper attack helicopters and Bell UH-1Y Venom utility helicopters. Nicknamed the "Stingers", the squadron is based at Marine Corps Air Station Camp Pendleton in California, and falls under the command of Marine Aircraft Group 39 (MAG-39) and the 3rd Marine Aircraft Wing.

The 1st Marine Logistics Group is a logistics unit of the United States Marine Corps and is headquartered at Marine Corps Base Camp Pendleton, California, with several subordinate elements located at Marine Corps Air Station Yuma and Marine Corps Air Ground Combat Center Twentynine Palms. It is the logistics combat element of the I Marine Expeditionary Force.

The 3d Marine Littoral Regiment is a regiment of the United States Marine Corps that is optimized for littoral maneuver in the Indo-Pacific Theater. Based at Marine Corps Base Hawaii, the regiment falls under the command of the 3rd Marine Division and the III Marine Expeditionary Force. It was known as the 3rd Marine Regiment from 1914 to 2022, when it was renamed as part of the Commandant of the Marine Corps' Force Design 2030 initiative. The 3d MLR has participated in the 2022 and 2023 Balikatan exercises in Northern Luzon, Philippines.

3rd Battalion, 3rd Marines, abbreviated as (3/3), was an infantry battalion of the United States Marine Corps, based out of Kaneohe, Hawaii. Known as either "Trinity" or "America's Battalion", the unit normally fell under the command of the 3rd Marine Regiment of the 3rd Marine Division. When fully manned, the unit consisted of approximately 1000 U.S. Marines and United States Navy Sailors. Like most 20th century model infantry battalions of the U.S. Marine Corps, 3rd Battalion 3rd Marines was made up of three rifle companies, Weapons Company and a Headquarters and Services (H&S) company. The battalion was originally formed at Marine Corps Base Camp Lejeune, North Carolina in 1942 and saw action on both Bougainville and Guam during World War II, where it was awarded its first Presidential Unit Citation and Navy Unit Commendation. Marines in the battalion were also awarded one Medal of Honor and seven Navy Crosses during the war.

2nd Battalion, 3rd Marines (2/3) was an infantry battalion in the United States Marine Corps based out of Marine Corps Base Hawaii consisting of approximately 1,000 Marines and sailors. The battalion fell under the command of the 3rd Marine Regiment and the 3rd Marine Division. The battalion was deactivated in January 2022 as part of the Marine Corps' ongoing Force Design efforts.

2nd Battalion, 11th Marines (2/11) is an artillery battalion comprising four firing batteries and a Headquarters Battery. The battalion is stationed at Marine Corps Base Camp Pendleton, California. Its primary weapon system is the M777 lightweight howitzer. The battalion was the first in the Marine Corps to fully transition from the M198 Howitzer. They fall under the command of the 11th Marine Regiment and the 1st Marine Division.

1st Battalion, 4th Marines (1/4) is an infantry battalion in the United States Marine Corps based out of Marine Corps Base Camp Pendleton, California consisting of approximately 800 Marines and sailors. They fall under the command of the 1st Marine Regiment and the 1st Marine Division.

The 1st Battalion, 6th Marines (1/6) is an infantry battalion in the United States Marine Corps based in Camp Lejeune, North Carolina. It consists of approximately 1,100 marines and sailors. They fall under the command of the 6th Marine Regiment, the 2nd Marine Division of the II Marine Expeditionary Force.

1st Battalion, 25th Marines (1/25) is a reserve infantry battalion in the United States Marine Corps located throughout New England and upstate New York and consisting of approximately 850 Marines and Sailors. The battalion falls under the 25th Marine Regiment in the 4th Marine Division.

3rd Assault Amphibian Battalion is one of two active duty assault amphibian battalions in the United States Marine Corps. The battalion is tasked with transporting US Marine forces and their equipment from assault ships to shore, and equipped with the Amphibious Combat Vehicle (ACV), which replaced the Amphibious Assault Vehicle (AAV). The battalion is part of the 1st Marine Division and the I Marine Expeditionary Force. The unit is based in Camp Pendleton in California.

2nd Battalion, 23rd Marines (2/23) is a reserve infantry battalion in the United States Marine Corps located throughout the Western United States consisting of approximately 1000 Marines and Sailors. They fall under the command of the 23rd Marine Regiment and the 4th Marine Division.

3rd Battalion, 24th Marines (3/24) was a reserve infantry battalion in the United States Marine Corps. The battalion was first formed in 1943 for service in the Pacific Theater of Operations during World War II, taking part in a number of significant battles including those at Saipan and Iwo Jima before being deactivated at the end of the war. In the early 1960s, the unit was reactivated as a reserve battalion. It was located throughout the Midwestern United States and consisted of approximately 800 marines and sailors. The battalion was part of the 24th Marine Regiment and the 4th Marine Division. Recent operations included tours in Iraq and Afghanistan. On May 19, 2013, the battalion was deactivated (retired) as a part of 2013 Marine Corps Force Restructuring, along with the 24th Marine Regiment. 3/24 personnel were reallocated to 23rd Marine Regiment, with the majority of the companies becoming 3rd Battalion, 23rd Marines.

The 9th Marine Regiment was an infantry regiment of the United States Marine Corps. Formed during World War II, it served until 1994, when it was deactivated during the post Cold War drawdown. Battalions of the Ninth Marine Regiment, but not the regiment itself, were reactivated from 2007 to 2014 as part of the Marine Corps' growth during the wars in Iraq and Afghanistan. The battalions have subsequently been deactivated again.

The 3d Medical Battalion is a medical support unit of the United States Marine Corps and is headquartered at Camp Foster, Okinawa, Japan. The unit falls under the command of 3rd Marine Logistics Group.

The 7th Engineer Support Battalion is an engineer support unit of the United States Marine Corps and is headquartered at Marine Corps Base Camp Pendleton, California. The unit falls under the command of 1st Marine Logistics Group and the I Marine Expeditionary Force.

1st Medical Battalion is a unit of the United States Marine Corps operated by the United States Navy that provides expeditionary Health Service Support to Marine Corps forces forward deployed to operations or humanitarian missions. The unit is based out of Marine Corps Base Camp Pendleton and falls under the command of 1st Marine Logistics Group.

The 3rd Battalion, 9th Marines (3/9) is an infantry battalion of the United States Marine Corps. Formed during World War I it served until the early 1990s when it was redesignated as 3rd Battalion, 4th Marines (3/4) during a realignment and renumbering of the Marine Corps' infantry battalions, following the deactivation of the 9th Marine Regiment. The 3rd Battalion, 9th Marines was initially a subordinate unit of the 9th Marine Regiment, 3rd Marine Division, but was later operationally transferred to the 1st Marine Division as a subordinate unit of the 7th Marine Regiment where it remained until its redesignation as 3/4.

Marine Unmanned Aerial Vehicle Training Squadron 2 (VMUT-2) is an unmanned aerial vehicle training squadron in the United States Marine Corps that is transitioning from operating the RQ-21A Blackjack to the MQ-9A Reaper. The squadron is based at Marine Corps Air Station Cherry Point in Havelock, North Carolina and will serve as the MQ-9A Reaper Fleet Replacement Squadron, training UAS officers and enlisted sensor operators. Historically, VMUT-2 provided aerial surveillance, offensive air support, and electronic warfare for the II Marine Expeditionary Force. VMUT-2 falls under the command of Marine Aircraft Group 14 and the 2nd Marine Aircraft Wing.