Headquarters and Maintenance Squadron 31 (H&MS-31) was a United States Marine Corps aviation support unit originally activated to provide administrative, supply, and intermediate aircraft maintenance support for Marine Aircraft Group 31 (MAG-31). The squadron was first established during World War II and played a critical role in ensuring the operational readiness of the group's aircraft in the Pacific Theater. Throughout the Cold War, H&MS-31 continued its mission, supporting Marine fighter squadrons at various locations, most notably at Marine Corps Air Station Beaufort, South Carolina. In the late 1980s, following a Corps-wide reorganization, H&MS-31 was redesignated as Marine Aviation Logistics Squadron 31 (MALS-31), continuing its legacy of vital aviation logistics support.