At what rank do you begin at O-1?

The rank at which an officer begins in the Navy is Ensign, which is classified as O-1. This is the entry-level officer rank for naval officers who have completed their commissioning programs, which may include the Naval Academy, ROTC, or Officer Candidate School. As an Ensign, an officer is expected to start their career in various capacities, usually under the supervision of more senior officers as they begin their operational training and career development.

Chief Warrant Officer, Chief Petty Officer, and Lieutenant Junior Grade are subsequent ranks. Chief Warrant Officer is a specialist rank that requires prior service and a different path of promotion, while Chief Petty Officer is an enlisted rank. Lieutenant Junior Grade follows Ensign and is the next step up, occurring after successfully demonstrating competencies expected of an Officer. Thus, Ensign is the correct starting rank for officers in the Navy.