The commissioned officer corps is divided into 10 pay grades [O-1 through O-10].  Officers in pay grades O-1 through O-3 are considered company grade officers.  In the Army, Marine Corps, and Air Force, these pay grades correspond to the ranks of second lieutenant (O-1), first lieutenant (O-2), and captain (O-3), and in the Navy, ensign, lieutenant junior grade, and lieutenant.  Officers in the next three pay grades (O-4 through O-6) are considered field grade officers.  In the Army, Marine Corps, and Air Force, these pay grades correspond to the ranks of major (O-4), lieutenant colonel (O-5), and colonel (O-6), and in the Navy, lieutenant commander, commander, and captain.  The last four pay grades are reserved for general officers in the Army, Marine Corps, and Air Force, and flag officers in the Navy.  The ranks associated with each pay grade are as follows: in the Army, Marine Corps, and Air Force, brigadier general (O-7), major general (O-8), lieutenant general (O-9), and general (O-10); in the Navy, rear admiral-lower half, rear admiral-upper half, vice admiral, and admiral.

As Table 4.2 shows, the force structure of the officer corps is that of a pyramid with the company grade officers making up the broad base (59 percent of officers in FY 1999), followed by field grade officers representing the narrower middle (41 percent of officers in FY 1999), and general/flag officers representing the pinnacle (less than 1 percent of officers in FY 1999).  This pay grade distribution is influenced not only by the military’s emphasis on youth and fitness, but also by the choices and competition engendered by “up or out” career progression policies.