Recruit Training Regiment provides for reception, processing and training of enlisted personnel upon their accession into the Marine Corps and develops the Drill Instructors and officers responsible for recruit training in order to transform recruits into Basically Trained Marines, prepared to meet the challenges of their follow-on training.
In 1921 the Marine Corps Recruit Depot San Diego was formally commissioned and in 1923, it became the primary recruiting center for the west coast. During World War II, the flow of recruits into the base surged, with 18,000 recruits arriving in one month. In 1948, the base was formally named Marine Corps Recruit Depot San Diego and was home to the Recruit Training Regiment.