The School of Infantry (SOI) is the second stage of initial military training for enlisted United States Marines after Recruit Training. Since the initial training pipeline is divided between coasts, Marines from areas east of the Mississippi River usually graduate from MCRD Parris Island and move on to SOI at SOI East (located at Camp Geiger, a satellite facility of Camp Lejeune in North Carolina), while those from the western half of the nation attend MCRD San Diego and move on to SOI West at the Camp San Onofre area of Camp Pendleton in California. Female Marines are an exception, all of whom go through MCRD Parris Island and SOI East.
The School of Infantry’s training mission ensures “Every Marine is, first and foremost, a Rifleman”. At SOI, Marines with the Military Occupational Specialty of infantry (0300 occupational field) are trained at the Infantry Training Battalion (ITB), while all non-infantry Marines are trained in basic infantry and combat skills at the Marine Combat Training Battalion (MCT Bn). SOI marks a transition in the professional training of entry-level students from basically trained Marines to combat-ready Marines.