A company officer (CO) is the individual in charge of a crew of firefighters and their responding apparatus in the United States. Company Officers have different titles depending on the table of organization for their particular agency, but commonly used titles in the U.S. Fire Service include Lieutenant, Captain, Sergeant, or other ranks which reflect the paramilitary organization of most departments.
Company Officers in U.S. career fire departments are generally promoted after passing a series of written tests, oral interviews, and tactical evaluations. A certain amount of time in service or time in grade is also often required before an individual is eligible to test for the next highest rank within the department. Seniority may determine whether an officer is in charge of one responding apparatus, or is in charge of an entire station where multiple fire apparatus are housed.
Officer ranks above the company officer level are frequently referred to as "Chief Officer" ranks. Whereas a Company Officer is generally involved with fireground tactical operations in addition to their supervisory duties, Chief Officers are rarely involved with hands-on fireground operations.