Officer Candidates School (United States Marine Corps)

The United States Marine Corps Officer Candidates School (OCS) is a training regiment designed to screen and evaluate potential Marine Corps officers at Marine Corps Base Quantico in Virginia. Those who successfully complete the period of instruction are commissioned as second lieutenants.

Most Marine Corps officers earn their commissions through OCS, though others are midshipmen from the United States Naval Academy, limited duty officers and warrant officers, and inter-service transfers. This differs from the other United States military services, who commission the majority of their officers through the Reserve Officers’ Training Corps (ROTC) programs at various colleges.

Officer candidates go through a 10-week Officer Candidates Course (OCC) or Platoon Leaders Class (PLC), or two 6-week PLC courses over separate summers, designed primarily to screen and evaluate candidates' physical and mental capabilities to lead Marines by placing them in leadership positions and physically and mentally demanding environments. The second 6-week course only happens after a candidate's junior year of college. The OCC 10-week course is available to those seeking a commission who meet the requirements to become an officer to include already possessing a bachelor's degree. Students are evaluated during two- to three-day garrison command billets at the company, platoon, and squad level, and fire-team level tactical billets during field exercises and situational leadership events.