Ranks of a Non-Commissioned Officer (NCO) in the United States Army, Marine Corps and Air Force. The pay grade for these two ranks is E8 for Army and Marine Corps and E7 for the Air Force (there is only a Master Sergeant for the AF, but also a Senior Master Sergeant at E8).

The main difference between First and Master Sergeant, is that the First Sergeant is more "visible", a father figure of sorts. Greater leadership qualities are expected of the FS than the MS, and he ranks slightly higher because of that.

A First Sergeant will command a whole troop unit, hold formations, instruct platoon sergeants, advises the Commander and assists in the training of all enlisted members of his command.

A Master Sergeant does not hold all of these duties, but still acts as the principal NCO at battalion (and sometimes higher) level. He is expected to strive towards goals as hard as the FS, and achieve the same results.

A Master Sergeant's insignia is characterized by 3 bent horizontal stripes (chevrons) and 3 bowed lines underneath (rockers). The First Sergeant's insignia is the same, but is complemented by the outline of a diamond in the middle (device). In the Marine Corps that diamond is instead two crossed rifles.

See also: E7, E8, Rank and Pay Grades of the US Military