This thesis considers the experience of being an official in the Seleucid empire. The empire could not function without the many administrative officials who served the Seleucid kings, for they in their roles as royal representatives and managers of information, infrastructure, wealth and political networks held together the many different regions and peoples under Seleucid rule. By understanding their experience of wielding ruling power on behalf of the kings, we may gain a better sense of how Seleucid rule operated, not just as a governmental structure but as it affected and worked through the lives of the people involved. The discussion of officials is not biographical, but a characterisation of types of officials according to their experiences of hierarchy and participation in rule and a comparison of official types on the basis of differing experiences and circumstances. The available evidence for Seleucid administration, much of it epigraphical, is analysed for the patterns of experience linking together Seleucid officials across the history and distances of the empire, and from these patterns several points are asserted. The experience of office-holding under the Seleucids was characterised by a relationship to the king, who was responsible for appointing his officials to particular titles and decided in what capacity they would act as his agents. The work of Seleucid officials was effected through formalised documentary practices, by which they managed information throughout the communities of the empire and communicated with one . another regarding royal policies and decisions in a politely authoritative language. Communication between officials resulted in frequent travel across the empire by couriers, ambassadors and by the royal court itself, and the logistics of travel by officials built up a conceptualisation of Seleucid space as a governed unit, distinguishable by the presence of officials holding regions together by their links with one another and with the kings. In their control of space and territory the Seleucid officials dealt with resources, and applied their documentary practices to manage lands, revenues and taxation on behalf of the kings whose wealth it was, and for themselves. There was prestige and political power to be derived from control of wealth, seen in the business of officials at royal treasuries and mints, and in the pattern of coinage circulation and the habit of acquiring control of local mints by individuals whose power in the Seleucid organisation led them to obtain independent authority. The political experience of Seleucid officials were characterised by their membership as a class of elites in the formal friendship networks of the Greco-Macedonian world, networks which expanded to the fringes of the empire along lines of internal diplomacy. The communication and travel routes across the empire and the formal documentary language used by officials enabled them to build political links within the empire by facilitating material and honorific reciprocity and strengthening the hierarchical relationships of the administration. The vibrancy and success of the Seleucid administrative experience as a route to political gains is witnessed by the examples of officials who attained to independent rule themselves or had influence over the course of Seleucid history