The emperor Diocletian (A.D 284-305) established an entirely new system of governing the Roman world, which is known today as the "Tetrarchy." Diocletian's system saw four men, twoAugusti and two Caesars, sharing control of the Roman Empire and basing themselves in different geographical locations. As such, the Tetrarchs were able to deal with threats to the Empire's borders much more efficiently than one emperor. In order to contrast the Tetrarchs from the civil wars and usurpations of the fifty years that had preceded them, a new system ofimperial representation was developed. This thesis examines surviving examples of Tetrarchic imperial representation. This includes coins and medals of the Tetrarchs, porphyry statue groups, a monument of five columns in the Forum Romanum (the F nfs(ulendenkmal), the Arch of Galerius in Thessalonike, wall paintings at Luxor, and the so-called Arcus Novus in Rome. Onall of these monuments, the Tetrarchs are consistently shown as four equal emperors, but a single ruling unit. The new portraiture, costume and attributes of the Tetrarchs are thought to beintended to show the Tetrarchs as identical and equal. This concept, termed similitudo, was used to underscore the ideal of Tetrarchic harmony (concordia). Jupiter and Hercules find a specialplace in Tetrarchic representation as the patrons of the two Tetrarchic houses. The use of other personifications and divinities in Tetrarchic representation showed the divine prerogative, legitimacy and the universality of the Tetrarchic system. It is argued that Tetrarchic art and monuments do not represent a decline in Roman art as was once commonly thought. Instead, itseems that the Tetrarchy marks the beginning of a move towards more symbolic representation. The overall effect of these changes was to represent the Tetrarchs as a cohesive and powerfulruling unit.