Specialist, in the context of military forces following Earth naval tradition, is an enlisted title (or "rating" in traditional naval parlance.) It is not a rank. For example, in the old Earth United States Navy (the rank structure and titles of which are largely the basis for Starfleet's ranks), an "Operational Specialist" (which is one of several different Specialist ratings) denotes enlisted personnel who work in a Combat Information Center (CIC), the tactical "nerve center" of a ship. Using a wide variety of assets available to them, these particular specialists are responsible for the organized collection, processing, display, competent evaluation and rapid dissemination of pertinent tactical combat information to command and control stations, upon which sound tactical decisions may be made.
Starfleet gives non-commissioned authority to different rates of specialists, such as "specialist first class", "specialist second class", and "specialist third class". A specialist who is promoted beyond chief petty officer could be referred to as "chief specialist", "senior chief specialist" or "master chief specialist" as they move through the noncom grades. Some specific types of specialists exist, and are referred to by their own titles. These include yeoman, chef, technician, sensor analyst, and nurse.
The term "specialist" can also be used as a title to refer to a higher ranked person who has been appointed a specialist in a position.
- Specialist Robert Tomlinson held the rank of lieutenant while part of the ship's phaser crew aboard Enterprise in 2266. (TOS: "Balance of Terror").
- Robin Lefler was an ensign when named to specialist position in 2368. (TNG: "The Game")