The 0321 Reconnaissance Marine is the primary MOS for all enlisted Reconnaissance and Force Reconnaissance Marines in the Marine Corps.

The Reconnaissance Marine is an Infantry Marine skilled in amphibious reconnaissance and ground reconnaissance & surveillance. In addition to basic infantry skills, reconnaissance Marines possess enhanced physical and psychological attributes required to gain access to the operational environment and are required to maintain advanced capabilities in combat swimming; small boat operations; highly-refined scouting and long range patrolling; close combat skills; demolitions; forward observer
procedures for supporting arms; ITG operations for heliborne, airborne, and waterborne forces; long-range communications; imagery collections; threat weapons and equipment identification.

All Reconnaissance Marines receive advanced training in survival escape resistance evasion (SERE), low level static line (LLSL) parachuting, military freefall parachuting and combatant diving. They are also trained as a subject matter experts in advanced communications, special weapons, joint terminal attack control, helicopter-rope insertion/extraction techniques, assault climbing, intelligence collection, mountain warfare, method of entry, sniper operations, advanced combat life support, close quarter tactics, jumpmaster's and dive supervisor's depending on their billet in the reconnaissance platoon.

Reconnaissance Marines contribute to the collection of intelligence at the tactical, operational, and strategic levels of war. They are highly capable of conducting clandestine missions in sensitive to non-permissive environments. Employed as part of the Marine Air-Ground Task Force, Joint Task Force or Joint force, Reconnaissance Marines provide timely intelligence to the supported commander to shape and influence the battlefield. The varying types of missions a Reconnaissance Marine conducts are amphibious reconnaissance, ground reconnaissance and surveillance, battle space shaping, limited specialized raids and other special reconnaissance missions by using special insertion extraction techniques to include: surface, subsurface and airborne operations as required.