The firms were given the letters C through I and K through P. To avoid confusion with the similar "I" (or India) designation on typed documents, there was no "J" Ranger Company.

The Ranger companies were composed of small, heavily armed long range reconnaissance teams that patrolled deep in enemy-held territory.

Each independent company was attached to a separate division or brigade and acted as the eyes and ears of those units.

Additionally, Rangers attempted to recover prisoners of war, capture enemy soldiers for interrogation, tap the wire communications of the North Vietnam Army and the National Liberation Front for South Vietnam (Vietcong) on the Ho Chi Minh trail, and mine enemy trails and roads.

When they were redesignated on 1 February 1969, the average TOE strength of a Ranger company was of 3 officers and 115 enlisted men, bringing the total to 118 men divided into a company headquarters, operations section, communications platoon, and two patrol platoons.