Marines in the Reserve go through the same training and work in the same Military Occupational Specialties (MOS) as their active-duty counterparts.

[3] The United States Marine Corps Reserve was established when Congress passed the Naval Appropriations Act of 29 August 1916, and is responsible for providing trained units and qualified individuals to be mobilized for active duty in time of war, national emergency, or contingency operations.

The IRR is composed of Marines who have finished their active duty or USMCR obligations, however, their names remain on record to be called up in case of a war or other emergency – the Individual Ready Reserve is administered by the Marine Corps Individual Reserve Support Activity.

They then have a mandatory leave of 10 days (up to 24 if they volunteer for and are assigned to recruiter's assistance, although, reservists are not usually given RA) before further training at the School of Infantry (SOI) and their designated Military Occupational Specialty (MOS).

For those who have earned a college degree, the Reserve Officer Commissioning Program (ROCP) provides a path directly into the Marine Corps Reserve leading to a commission as an officer of Marines.

[8] The mission of the Prior Service Recruiter is to join members from the Individual Ready Reserve to SMCR units close to their home.

[8] Marine reservists are allowed to serve simultaneously in the United States Marine Corps Reserve and in the naval militia of their state of residence; however, when called into federal service, reservists are relieved from service and duty in the naval militia until released from active duty.