The Guam National Guard is the National Guard in the United States territory of Guam, made up of the Guam Army National Guard and the Guam Air National Guard.
The National Guard of the Island of Guam can be traced back to the first military organization on the island known as the Guam Militia. The Guam Militia was first organized by Governor Mariano Tobias during the Spanish colonial period on Guam in 1771 but was disbanded in 1885. It was later reestablished on March 25, 1917, under U.S. Naval Governor Roy C. Smith because island residents requested more physical and military training be required of their younger male population. Thus, it became mandatory for males, 18 years or older, to attend drills on Sundays from 8 a.m. to 11:30 pm. at the Plaza de Espana in Hagatna. As a quasi-military force, the unit members were neither compensated nor provided with uniforms and equipment.