Named for Senator John Morris Sheppard (D) (1875-1941), a US Senator from Texas and political leader in US military preparedness in the days leading to the attack on Pearl Harbor, Sheppard Field was opened in October 1941, only eight weeks before a sudden attack of the sort the Senator was concerned about. Sheppard Field had an initial mission of technical training, mainly aircraft mechanics. the first class of mechanics graduated in February 1942, and had the war waiting. Sheppard rapidly expanded training courses to include basic pilot training, glider mechanic training, technical and flying instructors, artillery spotter flight training, and training B-29 Superfortress flight engineers. The base's facilities were behind schedule for much of the war, with cramped housing; often barracks were used as training rooms. The base also trained Free French as mechanics, to support their own country's forces in exile.

Late in the war, the base trained advanced pilot school, and very early helicopter pilot and mechanic training. In all over 42,000 mechanics, plus 1,800 glider mechanics, graduated Sheppard's programs by war's end. At the end of the war became one of many service separation centers. This mission completed, Sheppard Field was declared surplus, transferred to the US Army Corps of Engineers, who used it with the National Guard for two years.

In 1948 Sheppard Field was transferred to the US Air Force as a supplemental training center for Lackland Air Force Base, which was expanding in response to the building Cold War. The Field was reopened as Sheppard Air Force Base, initially to provide basic training for incoming airmen. The arrival of the Korean War cemented the need for training centers, and Sheppard again began training aircraft mechanics for US forces and allied nation forces, notably Greece and Turkey, for service in Korea.

This need dropped rapidly in 1953, and Sheppard entered a phase of rebuilding. Housing, training facilities, a base exchange, and runway improvements followed. The technical requirements of the Cold War were different from World War Two, and Sheppard took on technical training in missile maintenance, civil engineering, transportation, comptrolling, and intelligence analysis. Sheppard's tradition of Allied training continued as well, from a large number of nations worldwide.

In the 1960s helicopter pilot and mechanical training returned to Sheppard for six years, until this training transferred to Army pilots at another base. At about the same time, Sheppard gained a large percentage of the field medical training for the Air Force, a mission that went hand in hand with helicopter training, for medevac. Helicopter training moved on, and in the 2000s medical training was transferred as well, although the 82nd Medical Group remains.

Over the years, Sheppard has been a primary training facility for allied and friendly nation's troop, starting with the Free French, later Greek and Turkish troops, and in the 1960s and 1970s El Salvador, Saudi Arabia, Ecuador, and until the Iranian Revolution, Iran. Training resource realignment in the 1970s and 1980s led to most aircraft maintenance training pooling at Sheppard, and a transfer of missile maintenance to another base. In the post-Cold War World and early 21st Century Sheppard AFB continues it's lifelong mission of whole system maintenance for a variety of aircraft.