First sergeant First sergeant is the name of a military rank used in many countries , typically a senior non - commissioned officer . Singapore . First Sergeant is a Specialist in the Singapore Armed Forces . First Sergeants are the most senior of the junior Specialists , ranking above Second Sergeants , and below Staff Sergeant s . The rank insignia for a First Sergeant features the three chevrons pointing down shared by all Specialists , and two chevrons pointing up . In combat units , First Sergeants are often given the responsibility for independently - operating detachments of support weapons . They are often given instructional billets as well . United States . In the United States , First Sergeant is the title given to holders of certain ranks and positions within the United States armed forces that equate to a Company Sergeant Major , and generally serve as the senior enlisted advisor of a unit . While the specifics of the title may differ between the United States Army , Marine Corps and Air Force , all first sergeants can be identified by the presence of a lozenge ( colloquially " diamond " ) shaped figure on their rank insignia United States Army . In the United States Army , the rank of First Sergeant ( abbreviated 1SG ) is above the rank of Sergeant First Class and below the rank of Sergeant Major . It is equal in grade to Master Sergeant , although the two ranks have different responsibilities , with a First Sergeant being senior to a Master Sergeant . The rank is abbreviated as " 1SG " in the Army . Master sergeants are laterally promoted to first sergeant upon selection by the senior leadership at Department of the Army , depending on available billets and opportunities . Upon reassignment to a non - first sergeant billet , the soldier reverts to their original rank of master sergeant . First Sergeants are generally the senior non - commissioned officers of company ( battery , troop ) sized units , and are unofficially but commonly referred to as " first shirt " , " top " , " top sergeant " , " top soldier " , " top kick " , or " top hat " , due to their seniority and their position at the top of the company ' s enlisted ranks . They are sometimes referred to as " second hat " because the Company Commander may entrust them with important responsibilities , even over one of the company ' s lieutenant s . First Sergeants handle the leadership and professional development of their soldiers , noncommissioned officer development , manage pay issues , supervise administrative issues , manage the promotable soldiers within the company , and are the first step in disciplinary actions such as an Article 15 ( non - judicial punishment ) proceeding . A first sergeant may place a soldier under arrest in quarters in certain cases , as well as manage all of the daily responsibilities of running the company / unit . Until September 1942 , First Sergeant was a Grade 2 enlisted rank , equivalent to Technical Sergeant ; it was then elevated to Grade 1 , equivalent to Master Sergeant . United States Marine Corps . In the United States Marine Corps , First Sergeant ( abbreviated 1stSgt ) is one level above Gunnery Sergeant and one level below Sergeant Major and Master Gunnery Sergeant . It is equal in grade to Master Sergeant , although the two ranks have different responsibilities . A first sergeant has a command responsibility as a senior enlisted " advisor " , while master sergeants have technical responsibilities . Unlike the first sergeant and master sergeant programs in the U . S . Army , no lateral movement is possible between the two ranks in the Marine Corps ; rather a gunnery sergeant elects a preference on fitness reports , which are considered before promotion . A first sergeant is then eligible to be promoted to a sergeant major , while a master sergeant would be on the promotional track for master gunnery sergeant . The grade of first sergeant initially appeared in the Marine Corps in 1833 , when Congress created the grade of Orderly Sergeant ; 30 billets for the rank were established . In 1872 , the Corps replaced the title of orderly sergeant with the rank of first sergeant . The rank of first sergeant was another casualty of the rank realignment of 1947 . It was reestablished in 1955 . United States Air Force . In the United States Air Force , First Sergeant is not a rank , but a special duty held by a senior enlisted member of a military unit who reports directly to the unit commander . This billet is held by individuals of pay grades E - 7 through E - 9 ( Master Sergeant , Senior Master Sergeant and Chief Master Sergeant ) , and is denoted on the rank insignia by a lozenge ( known colloquially as a " diamond " ) . Often referred to as the " first shirt " , or " shirt " , the first sergeant is responsible for the morale , welfare , and conduct of all the enlisted members in a squadron and is the chief adviser to the squadron commander concerning the enlisted force . Most units have a master sergeant in this position , while larger units use senior master sergeants and chief master sergeants as first sergeants . Law Enforcement . Some law enforcement agencies , especially state police and highway patrol organizations have first sergeants , who are typically in charge or command of a detachment , district or post consisting of anywhere from ten to fifty or more troopers or officers . Some such state agencies may have a first sergeant in charge of special state police units such as SWAT , K - 9 , aviation personnel , detectives and others . Some municipal and county agencies also have a first sergeant . Civil police first sergeants are senior to sergeants and junior to lieutenants . The insignia of such a first sergeant is usually similar to a military first sergeant but may only may have a chevron of three stripes with no rockers or just one or two rockers , but generally always have the lozenge under the chevrons .