Colonel

In the United States Marine Corps and the United States Colonel is a senior officer, with the pay grade of O-6. Colonel ranks above Lieutenant Colonel and below Brigadier General. Colonel is equivalent to a captain in the other uniformed services.

Modern American colonels usually command infantry brigades, USAF groups or wings, and USMC regiments. An Army colonel typically commands brigade-sized units (3,000 to 5,000 Soldiers), with a Command Sergeant Major as principal Non-Commissioned Officer assistant. An Air Force colonel typically commands a wing or consisting of 1,000 to 3,000 airmen with a Command Chief Master Sergeant as principal NCO advisor. Some Colonels are commanders of groups, which are the major components of wings. Colonels are also found as the chief of staff at divisional level-(Army) or Numbered Air Force-level staff agencies.

In the modern United States armed forces, the Colonel's eagle is worn facing inwards with head and beak pointing towards the wearer's neck. Of all US Military commissioned officer rank, only the Colonel's eagle has a distinct right and left insignia. All other commissioned officer rank insignia can be worn on either the right or left side.

Colonels are sometimes referred to (but not addressed) as "full-bird" or "O-6" (which is their pay grade) in order to differentiate between Colonels and Lieutenant Colonels, since Lieutenant Colonels are also referred to and addressed as simply "Colonel". In the Army a Colonel who has been selected for promotion to Brigadier General is authorized to use Colonel (P) (as in Promotable) when signing official documents. All other branches the officer still uses Colonel until the date of his actual promotion.