This dissertation studies the effects that a “koinon” in the Roman period could have on its constituent communities. The study traces the formation process of the koinon in Roman coastal Paphlagonia, called “the Koinon of the Cities in Pontus,” and its ability to affect local customs and norms through an assortment of epigraphic, literary, numismatic and archaeological sources. The results of the study include new readings of inscriptions, new proposals on the interpretation of the epigraphic record, and assessments on how they inform and change our opinion regarding the history and the regional significance of the coastal Paphlagonian koinon. This study finds that the Koinon of the Cities in Pontus in coastal Paphlagonia was a dynamic organisation whose membership and activities defined by the eparchic administrative boundary of the Augustan settlement and the juridical definition of the Pontic identity in the eparchic sense. The necessary process that forced the periodic selection of municipal peers to attain koinon leadership status not only created a socially distinct category of “koinon” elite but also elevated the koinon to extraordinary status based on consensus in the eparchia. The koinon, in turn, became a respected organisation and even a potentially useful political instrument for dictating honors and social standing, which could both prolong or accelerate individual and familial prominence at the eparchic or provincial level. As such, the coastal Paphlagonian koinon was a vital political instrument, with socio-political significance beyond the expression of loyalty to the imperial idea. It was an elite commission that determined local hierarchies and local standards based on collective consensus. The legitimacy of this elite commission emanated from the need to worship the emperor, but its power to influence or even control the behavior of individuals and cities originated from the socio-economic standing of the participating elites. In short, the founding of the koinon would have led to a redirection of local resources to the funding of koinon affairs and would have created regionally recognised norms derived from some of the established standards and behaviors among its constituent communities, while altering others.