Back in 1968, there was a concern that the Legion of Merit was being awarded too often, diminishing its prestige. What was needed was a new medal, one that be an equivalent to the Bronze Star, but would recognize non-combat achievement or service. Lyndon Johnson signed the executive order that established the Meritorious Service medal a year later, and Ronald Reagan amended its criteria in 1981 so recipients could include the military of friendly foreign nations.
Originally an award for peacetime activity, it was decided after 9/11 that it could also be given instead of the Bronze Star for meritorious achievement in a designated combat theatre.
In the Army and Air Force, recipients typically are field officers (majors, lieutenant colonels, and colonels) senior chief warrant officers, and senior non-commissioned officers. They're recognized for their performance in those roles or, for field officers, for exemplary completion of a command tour at the battalion or squadron level.
The Navy, Marine Corps, and Coast Guard usually award the medal to senior officers -- commander and captain for the Navy and Coast Guard, and lieutenant colonel and colonel for the Marine Corps -- although exceptions have been made for lower-ranking officers and/or retiring personnel.
Jay Morris of the Institute of Heraldry designed the complex bronze medal. The top half consists of six rays superimposed with the upper half of a five-pointed star, which in turn is etched with two smaller stars. The bottom of the medal is covered with bas-relief laurel leaves issuing from branches held in the talons of an eagle with outstretched wings. The laurel leaves represent achievement, the star denotes military service, and the rays, the effort of excellent service.
The medal hangs on a ribbon intentionally designed with the same colors as the Legion of Merit to show the connection between the two. Its plum ribbon features a white stripe one-eighth inch from either end.
Additional awards are recognized by bronze oak-leaf clusters (silver denoting six or more) for the Army and Air Force and gold stars (silver for six or more) for the Navy, Marine Corps, and Coast Guard.