More than 80% of the Marine Corps is made of enlisted Marines. The Officer Corps consists of the rest. This includes Commissioned Officers, Warrant Officers, and Limited Duty Officer. Noncommissioned Officers (NCOs) and Staff NCOs are still considered enlisted Marines. So what is the difference among all these officer types and how do you become one?
Officers in the military are appointed by the President of the United States and serve at his discretion. They are given their authority via a Commission or a Warrant (more on that in a moment).
This is what most people think of when they hear "officer." Officers are generally considered policy makers, leading units like Platoons, Companies, Battalions, etc. They also serve in staff roles as planners, operations officers, logistics officers, etc.
Commissioned Officer ranks are Second Lieutenant, First Lieutenant, Captain, Major, Lieutenant Colonel, Colonel, Brigadier General, Major General, Lieutenant General, and General.
To receive a commission, officers must graduate from Officer Candidate School or the US Naval Academy. They also need to be American Citizens and have a four-year college degree. They will commission as Second Lieutenants and attend The Basic School at Quantico to learn how to be Rifle Platoon Commanders before heading on to MOS School and the fleet.
Commissioned Officers can join directly from the civilian world or from the Enlisted ranks. Commissioning Programs include Naval Reserve Officer Training Corps - Marine Option, US Naval Academy, Officer Candidates Course, and Platoon Leader's Course.
Their MOS's are general to occupational fields such as Infantry Officer, Logistics Officer, Combat Engineer Officer, and Communications Officer. They are expected to understand the basics of the MOS's in their occupational field. There is usually one Commissioned Officer MOS per Occupational Field.
At the rank of Colonel, they will change their MOS to MAGTF Ground Officer, MAGTF Air Officer, or MAGTF Logistics Officer based on where they have spent their careers to date.
Warrant Officers are considered specialists as opposed to the general nature of Commissioned Officers. They come from enlisted ranks and are selected to become technical experts and leaders in their fields. Ranks include Warrant Officer, Chief Warrant Officer 2, Chief Warrant Officer 3, Chief Warrant Officer 4, and Chief Warrant Officer 5.
They have specific functions they fill and will only be assigned to roles in that functional area. Examples of Warrant Officers are Infantry Weapons Officer (also known as Gunners, who are experts on Infantry weapons and tactics), Engineer Equipment Officer (they only focus on the maintenance and repair of engineer equipment), Personnel Officer (they run administrative centers and personnel branches), and EOD Officer (specializing in explosive ordnance disposal).
Warrant Officers all come from Enlisted backgrounds. 95% of Warrant Officers come from the MOS they were enlisted in. The other 5% are typically reassigned to a new MOS which they must learn all over.
To become a Warrant Officer, enlisted Marines must apply at the rank of Staff Sergeant and be accepted. They will then attend the Warrant Officer Basic Course and The Basic School and promote to the rank of Warrant Officer.
As a Warrant Officer, your first two years are probationary. If your performance is unsatisfactory, you can be returned to your prior enlisted rank.
Limited Duty Officer
There are very few of these in the Marine Corps, but they do exist. An LDO is a Warrant Officer who has reached a command level specific to their MOS. Examples include Embarkation and EOD Warrant Officers. EOD Companies are headed by a Captain. This Captain would previously have been a Warrant Officer 3 or 4 who applied for a LDO position. They wear the same ranks as commissioned officers and are paid the same as well, but are limited to their specific occupational field like a warrant officer. LDO's usually have more than 20 years of service before they are selected.