Throughout its long history, the division has taken on numerous roles. Serving as the 100th Infantry Division until the 1950's, the division then briefly became the 100th Airborne Division before becoming the 100th Division (Training). Since this transformation, the division has primarily taken on numerous training roles for other Army units.

It was activated late in World War I, too late to join the fighting, but the division is best known for its exploits during World War II as the 100th Infantry Division. Fighting in the European Theater, the division advanced through France and Germany through the end of the war, fending off serious German counterattacks along the way. World War II would the only war the division would fight in before taking on its role as a training unit.