Prior to World War I, Marine Officers primarily came from the Naval Academy or from the enlisted ranks. The first officers training school at Quantico can trace its beginnings to 1891 when Marine Corps General Order No. 1 established the first formal resident school for Marine Officers, the "School of Application" at Marine Barracks, Washington, D.C. In 1909, the school moved to the Marine Barracks at Annapolis, Maryland, and was renamed the "Marine Officers School;" and, in 1910, it moved to Norfolk, Virginia.
With U.S. involvement in World War I came the increase in the size of all the Armed Services and the Marine Corps was no exception. To meet this need for qualified officers to serve with the American Expeditionary Forces in Europe, a decision was made to move the instructional effort to Quantico where individual replacements and new units were being formed for the war. Quantico was where all new officers were going and the "Officers Camp of Instruction," organized at Quantico in July, 1917, would be the place where they would receive their training. Its original location was near Barnett Avenue, approximately one half mile south of what is now the town of Quantico. In April of 1918, the school was formalized and titled the "Officers Training Camp."
In the fall of 1919, the Commanding General of Quantico, Major General John A. Lejeune, established the "Marine Corps Officers Training School" and the "Marine Officers Infantry School". These two schools were subsequently combined in 1920 to become the "Marine Officers Training School." By 1922, this school had further evolved into the "Field Officers Course" (modeled after the Army's Command and General Staff School) and the "Company Officers Course," both designed to teach tactics, topography, law, administration, and engineering, among other subjects. A third course, called "The Basic School" (TBS) was designed to indoctrinate new Marine lieutenants in the duties of infantry leaders.
It was during this period, having proved itself on the battlefields of France that a still growing Corps began recruiting potential officers from colleges and universities through the Naval Reserve Officer Training Corps (NROTC) Program with lieutenants commissioned from the U.S. Naval Academy, NROTC units, and qualified enlisted Marines who had been commissioned reporting to TBS for instruction. Officer training was further expanded and, in 1924 due to a shortage of suitable classrooms and officers' billeting at Quantico, TBS moved to Philadelphia. Although the school remained physically separated until its return to Quantico in World War II, it was firmly under Quantico's control.
In 1934, the Marine Corps developed the idea of the Platoon Leaders Class (PLC), selecting students from certain colleges that did not have a Reserve Officers Training Corps. In the spring of 1935, platoon leaders classes were organized at Quantico and San Diego. Under this new program, college graduates were appointed second lieutenants in the Marine Corps Reserve after two six-week training periods, and were given further training at TBS. Lieutenant Colonel Clifton B. Cates, a future Commandant, commanded the first 200 candidates at Quantico in July 1935. But the increasing needs of World War II expansion still could not be met, and in July 1940, Colonel Lemuel Shepard Jr., another future Commandant, headed a special unit tasked with training additional officer candidates. This unit soon became the "Officer Candidates Course" and was to train potential officers ". . . in the fundamentals of military discipline, and in the school of the soldier, squad, and platoon . . . and to select those qualified for commission to provide capable and well-fitted officers for the Marine Corps Reserve." Thus, shortly after World War II began, all the Corps' junior officer training, excluding aviators, was conducted at Quantico, including TBS functions performed in Philadelphia prior to the war.
The wartime demands of 1943 prompted the Commandant to establish temporary candidate detachments at Camp Elliot, California and at Camp Lejeune, North Carolina. The Platoon Leaders Class was reestablished in 1944, and except for a temporary move to Parris Island, South Carolina in 1951, it has remained at Quantico. The addition of the PLC program to officer candidate training led to another reorganization, and in 1944, the Officer Candidate Course was renamed the "Officer Candidates School."
By September 1945, TBS had reopened, and by 1947, through various reorganizations, had assumed responsibility for the training of all officer candidates, including those of the Platoon Leaders Class and the Naval Reserve Officers Training Corps. Coincident with these reorganizations, TBS moved from its first home on Barnett Avenue to Brown Field at the site of the old Airfield No. 2.
During World War II, potential Marine Corps Reserve women officers were trained at Mount Holyoke College and Smith College, both located in Massachusetts. The passage of the Women's Armed Service Integration Act in 1948 enabled women Marines to serve for the first time as members of the regular establishment. In 1949, to accommodate this new requirement for women officers, the Women Officer Training Course was established under the command of TBS.
TBS headquarters left Brown Field in early 1955 and moved to Camp Upshur where it could be closer to its training activities. With this move, the training of women officers, NROTC midshipmen, and PLC candidates was no longer a TBS responsibility. A newly formed unit, the "Training and Test Regiment," took over the training activities left behind at Brown Field, and became the unit responsible for training officer candidates of the various officer procurement programs. On 1 June 1963, the regiment was re-designated the "Officer Candidates School." The last reorganization occurred in 1977 when women officer training was placed under the command of Officer Candidates School.