Courses in Military Science and Tactics were first taught at Oregon State in 1872. In 1873 Captain Benjamin D. Boswell was appointed Professor of Military Science and Tactics (1873-1876), the first U.S. Army officer on active duty to hold such a position in any land grant college in the West. The first cadet uniforms, worn at all times by male students, were gray with caps of the Civil War type. The more familiar blue uniforms were adopted in 1893.

ROTC at Oregon State University is made up of the Departments of Military Science, Naval Science, and Air Force Studies. In 1917, the Department of Military Sciences became responsible for all military training under the National Defense Act of 1916. The act expanded and standardized the training of Army Officers by colleges and universities and established the Reserve Officer Training Corps (ROTC). During World War II, OSU became known as the "West Point of the West" for commissioning more officers than any other non-military academy in the nation. At the end of World War II, the Secretary of the Navy commissioned the Department of Naval Science (ROTC) on this campus to provide the training of both Navy and Marine Corps officers. On July 1, 1949, the U.S. Air Force activated an AFROTC unit that is now called the Department of Air Force Studies. As of 1999, OSU is one of only 48 colleges and universities that offers education for all three military departments.

Originally, two years of military science and tactics were required of all able-bodied male students, but since 1962, ROTC has been voluntary. Since 1965, two-year programs have been available for students who have finished two years of college but have not taken ROTC previously.