A non-commissioned officer (sometimes spelled noncommissioned officer, abbreviated to NCO or non-com (US)), called a sub-officer in some countries, is a military officer who has not been given a commission. Non-commissioned officers, in the English-speaking world, usually obtain their position of authority by promotion through the enlisted ranks.
The NCO corps usually includes all grades of corporal and sergeant; in some countries, warrant officers also carry out the duties of NCOs. The naval equivalent includes some or all grades of petty officer, although not all navies class their petty officers as NCOs. There are different classes of non-commissioned officer, including junior non-commissioned officers (JNCO) and senior (or staff) non-commissioned officers (SNCO).
The non-commissioned officer corps is often referred to as "the backbone" of the armed services, as they are the primary and most visible leaders for most military personnel. Additionally, they are the leaders primarily responsible for executing a military organization's mission and for training military personnel so they are prepared to execute their missions. NCO training and education typically includes leadership and management as well as service-specific and combat training.
Senior NCOs are considered the primary link between enlisted personnel and the commissioned officers in a military organization. Their advice and guidance is particularly important for junior officers, who begin their careers in a position of authority but generally lack practical experience.
 National usage
An experienced NCO corps is a key component of Western armies.
In the Australian Army, the NCOs perform most of the physical duties and management. Lance corporals and corporals are called junior NCOs, while sergeants, staff sergeants, warrant officers class two and one are classified as senior NCOs. Officers in the Australian Army perform paper work duties whilst in a barracks environment while the NCOs ensure discipline is being maintained. In battle, it is the senior NCOs that ensure the soldiers are doing their job, while the officers are looking at the wider picture.
In the New South Wales Police Force, NCOs perform supervisory and coordination roles. The ranks of probationary constable through to leading senior constable are referred to as "constables". All NCOs within the NSW Police are given a warrant of appointment under the Commissioner's hand and seal.
All officers within the Australian Defence Force Cadets are non-commissioned. ADFC officers are appointed by the Director-General of their respective branch.
In the Canadian Forces, the Queen's Regulations and Orders formerly defined a non-commissioned officer as "A Canadian Forces member holding the rank of Sergeant or Corporal." In the 1990s, the term "non-commissioned member" (NCM) was introduced to indicate all ranks in the Canadian Forces from recruit to chief warrant officer.
By definition, with the unification of the CF into one service, the rank of sergeant included the naval rank of petty officer 2nd class, and corporal includes the naval rank of leading seaman; Corporal also includes the appointment of master corporal (naval master seaman).
NCOs are officially divided into two categories: junior non-commissioned officers, consisting of corporals/leading seamen and master corporals/master seamen; and senior non-commissioned members, consisting of sergeants and petty officers 2nd class. In the Royal Canadian Navy, however, the accepted definition of "NCO" reflects the international use of the term (i.e. all grades of petty officer).
Junior Non-commissioned officers mess and billet with privates and seamen; their mess is usually referred to as the junior ranks mess. Conversely, senior non-commissioned officers mess and billet with warrant officers; their mess is normally referred to as the warrant officers and sergeants mess (army and air force establishments) or the chiefs and petty officers mess (naval establishments).
As a group, NCOs rank above privates and below warrant officers. The term "non-commissioned members" includes these ranks.
In the Finnish Defence Force, NCO's (Aliupseeristo) includes all ranks from corporal (alikersantti, lit. sub-sergeant) to sergeant major (sotilasmestari, lit. soldiermaster). Ranks of lance corporal (korpraali) and leading seaman (ylimatruusi) are considered not to be NCO ranks. This ruling applies to all branches of service and also to the troops of the Border Guard.
In 1983 the NCO corps, since 1972 called the Platoon Officer Corps, was disbanded and its members were given commissions as officers in ranks of second or first lieutenant in Sweden's new one-tier military leadership system. In 2009 a similar system as the NCO corps was re-established, called "specialist officers". Direct recruitment from civilian life is followed by basic and preparatory leadership training, and advanced leadership training during 1.5 year as a specialist cadet at the military academy in Halmstad, a warrant as an OR-6, followed by specialist technical training. Swedish specialist officers have relative ranks that matches the commissioned officers; an OR-7 takes precedent over a second lieutenant, for instance.
In Germany and German-speaking countries like Austria, the term Unteroffizier (meaning: "lower officer" or sub-officer) describes a class of ranks between normal enlisted personnel (Mannschaften or in Austria Chargen) and officers (Offiziere). In this group of ranks there are, in Germany, two other classes: Unteroffiziere mit Portepee (with sword-knot) and Unteroffiziere ohne Portepee (without swordknot), both containing several ranks, which in Austria would be Unteroffiziere (NCOs) and Höhere Unteroffiziere (senior NCOs).
 New Zealand
In the New Zealand Defence Force, a non-commissioned officer is defined as:
- "(a) In relation to the Navy, a rating of warrant officer, chief petty officer, petty officer, or leading rank; and includes—
- (b) In relation to the Army, a soldier above the rank of private but below the rank of officer cadet; and includes a warrant officer; and also includes—
- (i) A non-commissioned officer of the Navy or the Air Force attached to the Army; and
- (ii) A person duly attached or lent as a non-commissioned officer to or seconded for service or appointed for duty as a non-commissioned officer with the Army:
- (c) In relation to the Air Force, an airman above the rank of leading aircraftman but below the rank of officer cadet; and includes a warrant officer; and also includes—
- (i) A non-commissioned officer of the Navy or the Army attached to the Air Force; and
- (ii) A person duly attached or lent as a non-commissioned officer to or seconded for service or appointed for duty as a non-commissioned officer with the Air Force:" – Defence Act 1990, Sect 2 (Interpretation)
In the Singapore Armed Forces, the term "non-commissioned officer" is no longer officially used, being replaced with Specialist. The term NCO however is still frequently used unofficially among the army.
 United Kingdom
In the British Armed Forces, NCOs are divided into two categories. lance corporals (lance bombardier, depending on unit) and corporals (lance sergeant, bombardier, lance corporal of horse) are junior NCOs. Sergeants (corporal of horse, serjeant) and staff sergeants (colour sergeant and staff corporal) (and in the RAF chief technicians and flight sergeants) are senior NCOs.
Warrant officers are often included in the senior NCO category, but actually form a separate class of their own, similar in many ways to NCOs but with a royal warrant. Senior NCOs and WOs have their own messes, which are similar to officers' messes (and are usually known as sergeants' messes), whereas junior NCOs live and eat with the unranked personnel.
 United States
In the United States Army, United States Air Force, and United States Marine Corps, all ranks of sergeant are termed NCOs, as are corporals in the Army and Marine Corps. A Marine Corps lance corporal is not considered an NCO. The rank of corporal (E-4) in the Army is a junior NCO, and is to be shown the same respect as any other NCO. In the United States Navy and United States Coast Guard, all ranks of petty officer are so designated. Junior NCOs (E-4 through E-5 grade), or simply "NCOs" (E-4 and E-5 only) in USMC usage, function as first-tier supervisors and technical leaders.
NCOs serving in the top three enlisted grades (E-7, E-8, and E-9) are termed senior non-commissioned officers (chief petty officers in the Navy and Coast Guard). Senior NCOs are expected to exercise leadership at a more general level. They lead larger groups of service members, mentor junior officers, and advise senior officers on matters pertaining to their areas of responsibility. A select few senior NCOs in paygrade E-9 serve as Senior Enlisted Advisors to senior commanders in each service (e.g., major command, fleet, force, etc.) and in DoD (unified commands, e.g., STRATCOM, EUCOM, PACOM, etc., and DoD agencies, e.g., DISA, DIA and NSA. One senior E-9, selected by the service chief of staff, is the ranking NCO/PO in that service, holds the highest enlisted rank for that service, and is responsible for advising their service secretary and chief of staff. One E-9 holds a similar position as the SEA to the Chairman of the Joint Chiefs of Staff. Senior enlisted advisors, service enlisted advisors and the SEA to the Chairman advise senior officer and civilian leaders on all issues affecting operational missions and the readiness, utilization, morale, technical and professional development, and quality of life of the enlisted force.
Within the United States Marine Corps, senior NCOs are referred to as staff noncommissioned officers and also include the rank of staff sergeant (E-6). SNCOs are those career marines serving in grades E-6 through E-9. The ranks include staff sergeant, gunnery sergeant (E-7), master sergeant / first sergeant (E-8), and master gunnery sergeant / sergeant major (E-9).
Unlike warrant officers in other militaries, warrant officers in the United States Armed Forces are considered specialty officers and fall between non-commissioned and commissioned officers. Warrant officers also have their own rank tier and paygrade. However, when warrant officers achieve the rank of chief warrant officer (CWO2) or higher, they are commissioned and are considered commissioned officers just like any other commissioned officer, but are still held in a different paygrade tier. They are entitled to salutes from their juniors, an officer's saber and uniform, but for much of the Uniform Code of Military Justice (UCMJ) are considered on par with NCOs.
 Related abbreviations
- NCOA: Noncommissioned Officers Association (U.S.)
- NCOA: Noncommissioned Officers Academy (U.S.)
- NCOER: Noncommissioned Officer Evaluation Report (Department of the Army FORM 2166-8)
- NCOIC: Non-Commissioned Officer in Charge (U.S./UK/Canada)
- NCA: Noncommissioned Aircrew (UK)
- SNCO: Senior Noncommissioned Officer
 See also
- "non-commissioned officer – definition of non-commissioned officer by Macmillan Dictionary". Macmillandictionary.com. Retrieved 2012-07-10.
- "NCO – Definition from Longman English Dictionary Online". Ldoceonline.com. Retrieved 2012-07-10.
- "Definition of non-commissioned – Oxford Dictionaries (British & World English)". Oxford Dictionaries. Retrieved 2012-07-10.
- "Chambers | Free English Dictionary". Chambersharrap.co.uk. Retrieved 2012-07-10.
- General Sir Mike Jackson (September 2003). "Cream Paper 46: The Role of the Non Commissioned Officer in the British Army" (PDF). UK Defence Forum. Retrieved August 19, 2010.
- Chapman, Jordan (August 18, 2009). "Building the NCO Backbone". www.army.mil. Retrieved August 19, 2010.
- "Volume 1 – Administration: Chapter 1 Introduction and Definitions" (PDF). Queen's Regulations and Orders for the Canadian Forces. Assistant Deputy Minister (Finance and Corporate Services), Department of National Defence/Canadian Forces. 9 October 2008. p. 6. Retrieved August 19, 2010.
- Department of National Defence Canada Non-Commissioned Officer Rank Insignia 1967–1985. Canadian Military Police Virtual Museum. Retrieved on: 2011-12-07.
- New Zealand Defence Act 1990 No 28, Sect 2. New Zealand Legislation, reprint as at 7 July 2010. Accessed August 19, 2010.
- The Center for Advanced Studies of the U.S. Army Noncommissioned Officer (United States)
- A Short History of the NCO (United States)
- History of noncommissioned officers (United States)
- Educating Noncommissioned Officers: The history (United States)
- The United States Army Non-Commissioned officer's guide Field Manual FM7-22.7 (United States)
|United States enlisted ranks|
|Pay Grade →
Branch of Service ↓
|Air Force||AB||Amn||A1C||SrA||SSgt||TSgt||MSgt||SMSgt||CMSgt - CCM - CMSAF|
|Army||PVT||PV2||PFC||SPC - CPL||SGT||SSG||SFC||MSG - 1SG||SGM - CSM - SMA|
|Marine Corps||Pvt||PFC||LCpl||Cpl||Sgt||SSgt||GySgt||MSgt - 1stSgt||MGySgt - SgtMaj - SgtMajMarCor|
|Navy||SR||SA||SN||PO3||PO2||PO1||CPO||SCPO||MCPO - CMDCM - FORCM - FLTCM - MCPON|
|Coast Guard||SR||SA||SN||PO3||PO2||PO1||CPO||SCPO||MCPO - CMC - MCPOCG|