In the U.S. Marine Corps Lieutenant Colonel is a senior officer, with the pay grade of O-5. Lieutenant Colonel ranks above
Major and below
Colonel. Lieutenant Colonel is equivalent to a commander in the other uniformed services.
In the 21st century U.S. military, the rank of lieutenant colonel is usually gained after 16–22 years of service as an officer. As most officers are eligible to retire after 20 years active service, it is the most common rank at which career officers retire.
