The Efficiency Medal was instituted in 1930 for award to part-time warrant officers, non-commissioned officers and men after twelve years of efficient serivce on the active list of the Militia or the Territorial Army of the United Kingdom, or of the Auxiliary Military Forces throughout the British Empire. At the same time a clasp was instituted for award to holders of the medal upon completion of further periods of six years of efficient service.
The medal was struck in silver and is oval. The fixed suspender bar, a pair of laurel leaves, is affixed to the medal by means of a single-toe claw and a horizontal pin through the upper edge of the medal. The suspender is decorated on the obverse with a scroll-pattern bar, inscribed to indicate the military force in which the receipient was serving at the time of qualification for the award.
Six versions of the medal have been awarded, the sixth only in Canada. The obverse has a raised rim on all versions and bears the crowned effigy of the reigning monarch.