First Lieutenant is the second-lowest commissioned officer rank for the United States Army, Air Force, and Marine Corps. It is the equivalent of a Lieutenant Junior Grade (LTJG) in the Navy. The paygrade for this grade is O-2. A First Lieutenant is above a Second Lieutenant but below a Captain.
A First Lieutenant is a junior officer, and is also considered a Company Grade Officer among commissioned officers. A First Lieutenant generally has 2 - 6 years of service under their belt. An officer generally gets their promotion to First Lieutenant in a few years, sometimes after finishing training.
Standard Abbreviations
- Army - 1LT
- Air Force - 1st Lt.
- Marine Corps - 1Lt.
Insignia
In all of the three branches, First Lieutenant is represented by a rectangular, polished, silver bar. It is worn in varying places, ranging from epaulets on the shoulders to being pinned to the collar or cover, depending on the uniform and branch in question. In subdued insignia, for combat uniforms such as the BDU, the rectangular bar appears as matte black. It can be differentiated from the Second Lieutenant's subdued bar, because the 2nd Lt's is matte tan.
Forms of Address
A First Lieutenant, in speech, is usually referred to as just "Lieutenant." For example, "There is the Lieutenant" or "Lieutenant Smith will see you." In written correspondence, the full title or the appropriate abbreviation should be used before their name. There are slang terms in common use, as well: including, but not limited to "Luey" and "LT" (pronounced as EL-TEE). When answering questions, addressing them, or responding to orders from a First Lieutenant, an enlisted person or lower ranking officer would follow their response with a "Sir" or "Ma'am" as appropriate to the Lieutenant's gender. For example, "Good Morning, Sir" or "Yes, Ma'am." | 
