|Higher Rank:||Chief Counselor|
|[ Source ]|
Because of their training in psychology, technically the ship or facility's Counselor is considered part of Starfleet Medical. The Counselor is responsible for helping crew members with personal, psychological, and emotional problems.
Qualified psychiatrists have served aboard starships since the 23rd century, although occasionally the role of chief medical officer and counselor were combined, with medical officers also having expertise in space psychology; an example of this is Doctor Leonard McCoy, of the USS Enterprise and USS Enterprise-A. By the mid-24th century, starship and starbase crews included a dedicated counselor, who was responsible for the mental well-being of the crew and civilian staff.
At the captain's discretion, the a ship's counselor may be allowed to wear something other than their normal Starfleet uniform while on duty.
It is typically rare for small ships to carry more than one counselor aboard, who will usually serve as the Chief Counselor, even when there are no other counselors to be the 'chief' of.