The Missouri National Guard (MONG), commonly known as the Missouri Guard, is a component of the Army National Guard and Missouri State Department of the National Guard. It is composed of Army and Air National Guard units. The Department office is located in Jefferson City.

The Army National Guard (ARNG), in conjunction with the Air National Guard, is an organized militia force and a federal military reserve force of the United States Army. They are simultaneously part of two different organizations: the ARNG of each state, most territories, and the District of Columbia, as well as the federal ARNG, as part of the National Guard as a whole. It is divided into subordinate units stationed in each state or insular area, responsible to their respective governors or other head-of-government.