Marine Corps MOS descriptions: Everything you need to know

“Every Marine is a Rifleman” is the mantra of the Marine Corps. While strictly true, Marine’s must also select and train for a position in which they will serve most of their time in the Marine Corps. Military Occupational Specialities are selected in advance of boot camp and so it is important that poolee‘s research and consider all the positions and opportunities available to them and make a decision that works best for them.

M.O.S. stands for Military Occupational Speciality code. This 4 digit code is also accompanied by a descriptive title. The 4 digit code is used to identify the different positions within the Marine Corps. The first 2 digits represent the Occupational Career Code (the department under which that job falls within), the last two digits represent the actual specialty which the Marine will train for.

There are a multitude of jobs and occupational fields to consider and it can be overwhelming trying to estimate where would be the best fit. Areas of training or likely deployment, testing scores, personal interests, and areas where you’ve shown skill are all good places to start. More detail on the different MOS’s can be found on the official Marine MOS Manual. You should also discuss options with your Recruiter, loved ones and past and present service members to get a better idea of what would be a good fit.

When selecting a job within the Marine Corps, it is important to note that you are not guaranteed what you request. Even if you hold all the prerequisites and test scores,  all you can depend on is being assigned to the Occupational field of choice so try to keep an open mind. It is also important to note that the better you perform in the ASVAB, the more likely you are to get your preferred position. The Marine Corps wants each and every Marine to be the most successful, and will, therefore, assign a MOS that they believe you will be highly successful at.

Marine MOS Letter Combinations

When researching different Military Occupational Specialities, you will notice that all the MOSs are also preceded by another letter. Here’s an explanation of what these letter combinations mean.

• Basic MOS – This is the code assigned while in training for a PMOS.
• PMOS – A Primary MOS is used to identify the basic skills and knowledge of a marine and is their primary military job. It is usually required for career movement up to through the Occupational Field. It is easiest to think of it as the starting point job.
• NMOS – A necessary / non – PMOS means that there is at least 1 prerequisite PMOS required before consideration for this job. Additional skills are learned which build upon the skills learned in the initial PMOS. This is similar to promotion above the original starting point job.
• FMOS – A free MOS is a NMOS that can be filled by any Marine with any MOS. The additional skills to be learned are unrelated to the primary skills in PMOS. This is similar to a promotion but the starting position being irrelevant in consideration.
• AMOS – An Additional MOS is another Primary MOS that is awarded to a Marine who already holds a PMOS. Marines are not promoted in an AMOS. This is similar to holding 2 starting point jobs.

Frequently Asked Questions

Can I change my job or Marine MOS?

If you have not started basic training yet, you can change your MOS by simply asking your recruiter to do so. Once enlisted, it takes some paperwork in order to change your MOS. Submission of a personnel action form is required and approved by your chain of command. You can apply to change position after 2 years but you are not guaranteed that change. For the most part, changes do not occur as the Marine Corps spends a lot of resources to train you. Waiting until your contract is up and requesting a new MOS before reenlisting or serving on 2 deployments are generally seen as good ways to secure a change. You can also volunteer for overseas duty if you want to fast-track the process.

Are there reasons I am denied my MOS?

Outside of the Marines needs and demands, there are some reasons why particular Marines are denied their choice of MOS. Low scores on the ASVAB, not meeting the physical demands as well as color blindness or not being eligible for security clearance are all reasons for rejection for certain positions and so poolee’s should be alert to this when applying for particular MOSs.

What does signing an “open contract” mean?

An open contract means that the Marine Corps will choose what MOS you go into. You can state a preference later but there is no guarantee of getting it if you sign for an open contract. It does not necessarily mean you will get a job no one else wants, it usually is spread across the different fields. However, if you have any preference, you should try to specify it, as the MOSs are hugely varied.

What does my Marine MOS mean for promotion?

For enlisted Marines, promotion is based on their PMOS’s although if they achieve promotion to Staff Sergeant or beyond, all other MOS’s can be considered. This varies from the procedure for Officers.

When is training for an MOS?

Upon successful completion of Marine Corps Boot Camp Marines will receive ten days of leave before they head to the School of Infantry (SOI). Depending on what MOS a Marine is designated they will either receive training for their MOS at SOI or attend additional schooling after SOI.

Marine Corps MOS

Occupational Field Number	Occupational Field
01	MANPOWER AND ADMINISTRATION
02	INTELLIGENCE
03	INFANTRY
04	LOGISTICS
05	MARINE AIR GROUND TASK FORCE
06	COMMUNICATIONS
08	FIELD ARTILLERY
09	TRAINING
11	UTILITIES
13	ENGINEER, CONSTRUCTION, FACILITIES, AND EQUIPMENT
18	TANK, ASSAULT AMPHIBIOUS VEHICLE AND AMPHIBIOUS COMBAT VEHICLE
21	GROUND ORDNANCE MAINTENANCE
23	AMMUNITION AND EXPLOSIVE ORDNANCE DISPOSAL
26	SIGNALS INTELLIGENCE/GROUND ELECTRONIC WARFARE
27	LINGUIST
28	GROUND ELECTRONICS MAINTENANCE
30	SUPPLY CHAIN ADMINISTRATION AND OPERATIONS
31	DISTRIBUTION MANAGEMENT
33	FOOD SERVICE
34	FINANCIAL MANAGEMENT
35	MOTOR TRANSPORT
41	MARINE CORPS COMMUNITY SERVICES
43	PUBLIC AFFAIRS
44	LEGAL SUPPORT
46	COMBAT CAMERA (COMCAM)
48	RECRUITING AND RETENTION
55	MUSIC
57	CHEMICAL, BIOLOGICAL, RADIOLOGICAL AND NUCLEAR (CBRN) DEFENSE
58	MILITARY POLICE, INVESTIGATIONS, AND CORRECTIONS
59	AVIATION COMMAND AND CONTROL (C2) ELECTRONICS MAINTENANCE
60	AIRCRAFT MAINTENANCE
63	ORGANIZATIONAL AVIONICS MAINTENANCE
65	AVIATION ORDNANCE
66	AVIATION LOGISTICS
68	METEOROLOGY AND OCEANOGRAPHY (METOC)
70	AIRFIELD SERVICES
72	AVIATION COMMAND AND CONTROL OPERATIONS
73	NAVIGATORS AND UNMANNED AIRCRAFT SYSTEM OFFICERS/OPERATORS
75	PILOTS/NAVAL FLIGHT OFFICERS

Learn more about what you need to know before you get to Marine Corps Boot Camp or start physically preparing for boot camp with a former Parris Island Drill Instructor.