Twentynine Palms Strategic Expeditionary Landing Field or Twentynine Palms SELF (ICAO: KNXP, FAA LID: NXP) is a military use airfield located nine nautical miles (17 km) northwest of the central business district of Twentynine Palms, a city in San Bernardino County, California, United States. The SELF is the largest expeditionary airfield (EAF) operated by the United States Marine Corps. It is also known as the Twentynine Palms EAF and is located at the Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms.

The history of the Expeditionary Airfield (EAF) and its supporting units is closely interwoven. In March 1977, General Louis H. Wilson, the 26th Commandant of the Marine Corps, activated the EAF. The initial unit placed in charge of the EAF was designated Detachment MABS-11. Two years later, in July 1979, Detachment MABS-11 became operationally attached to Marine Wing Support Group 37 (MWSG-37) and was redesignated MWSG-37, Detachment Bravo in 1982. Originally, only a cadre of Marines provided caretaker support for the EAF between exercises. However, during October 1988 MWSS-173 was transferred from MCAS Kaneohe Bay to the Marine Corps Air Ground Combat Center, Twentynine Palms in support of the EAF. On 4 March 1993, MWSS-173 was deactivated and Aviation Ground Support Element (AGSE) was activated to continue operating and maintaining the EAF. On 1 April 1999, AGSE deactivated and was redesignated as Marine Wing Support Squadron-374 (MWSS-374). Currently the squadron is over 700 strong, and possesses the ability to operate a tactical airfield including air traffic control services and maintaining ground and weapons support equipment for aircraft.

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