A Limited Duty Officer (LDO) is an officer in the U.S. Navy or U.S. Marine Corps who was selected for commissioning based on his skill and expertise, and is not required to have a Bachelor's Degree. They are used in situations where it is desirable to introduce the type of strong, deckplate-level technical knowledge into the chain of command that can only be found in the enlisted and formerly enlisted Warrant Officers who work with the equipment on a daily basis (and, in fact, a candidate must be a First Class Petty Officer in order to apply to be an LDO in the Navy. Chief Warrant Officer 2 in the USMC). Thus, like a Warrant Officer, an LDO is considered a technical expert. For this reason, LDOs are used extensively in engineering departments as well as the Naval Nuclear Power Program. The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... United States Marine Corps Emblem The United States Marine Corps (USMC) is the second smallest of the five branches of the United States armed forces, with 170,000 active and 40,000 reserve Marines as of 2002. ... A Petty Officer is a noncommissioned officer or equivalent in many navies. ... A Warrant Officer (WO) is a member of a military organization holding one of a specific group of ranks. ...

An LDO will normally be assigned as a Division Officer or as a Technical Assistant, often progressing to become a Principal Assistant to the Department Head. The term "Limited Duty" refers not to an LDO's authority or standing within the department, but rather the LDO's ultimate career progression. Unlike an Unrestricted Line Officer (URL), an LDO cannot command a warship. An LDO, instead may eventually command a shore activity (such as Supervisor Shipbuilding), or be slated for other technical assignments of increasing responsibility. Unrestricted Line Officers are Officers of the Line in the U.S. Navy who are qualifed to command ships of the line (ships of war). ...

Unlike Warrant Officers or Staff Officers, an LDO wears the same uniform as an Unrestricted Line Officer of the same rank. Other than a difference in age, one would not be able to tell the difference between an URL and an LDO, with the exception of the LDO wearing ribbons and warfare insignia earned as an enlisted. Thus, the wearing of the navy's Good Conduct Medal or an Enlisted Surface Warfare Specialist (ESWS) pin, if the LDO has not yet earned his Surface Warfare Officer pin, could be a give away. However, even this could be misleading, since not all prior enlisted are LDOs or Warrants. The Good Conduct Medal is one of the oldest military decorations of the United States military. ... The Surface Warfare Badge is a military badge of the United States Navy which is issued to those Naval personnel who are trained and qualified to perform duties aboard United States surface warships. ... The Surface Warfare Badge is a military badge of the United States Navy which is issued to those Naval personnel who are trained and qualified to perform duties aboard United States surface warships. ...

Since LDOs are one path of enlisted career progression, many LDOs retain a bit of the enlisted "working man's pride." They sometimes joke that "LDO" stands for "Loud Dumb Officer" in order to draw a distinction between them and officers commissioned directly from college. There are also some, though increasingly few, among the Chief Petty Officer community who view LDOs with contempt if they were not yet CPOs when commissioned. They see it as a fault that the LDO "bypassed the Chief's Mess" and went to the wardroom. Chief Petty Officer is a noncommissioned officer or equivalent in many navies. ...