Shortly after CSU was founded, President Charles Ingersoll - a Civil War veteran - organized a group of students into the school's first drill team. In 1916, with the advent of World War I, Congress passed the National Defense Act, creating the Reserve Officers' Training Corps, more commonly known as ROTC. Participation in ROTC was an important part of student life from that point on, with CSU first operating an Army ROTC program and later becoming one of the first in the country to have an Air ROTC unit (which later became Air Force ROTC). Male CSU freshmen were required to participate in ROTC up until 1962, when President Bill Morgan responded to a call led by The Collegian to make the program voluntary. Women joined the cadet corps in 1969, and in 1987, the Air Force ROTC Detachment at the University of Northern Colorado merged with the one at CSU to form a single cadet corps.

Alumni of CSU's ROTC programs include Four-Star General Lewis "Uncle Lew" Walt (Class of '36), who went on to become assistant commandant of the Marine Corps and chief of U.S. Naval Forces in the Vietnam War. Today, about 400 cadets participate in the two CSU ROTC programs, which honor America before every event at Hughes Stadium and Moby Arena during our national anthem.