The second chapter provides an analysis of the Ionian Koinon, the association of the thirteen cities of Ionia, as one of the most direct and explicit channels for expressing Ionian cultural identity. Its festivals and ritual gatherings served both internally and externally as the most important means for making Ionianness visible. By discharging a koinon office, the civic elites of the koinon’s member cities were able to showcase their loyalty to a shared cultural affiliation and at the same time to engage in an inner-Ionian competition for euergetic prestige. This chapter also includes the first prosopographical study of all attested officials of the Ionian Koinon. It is concluded by a comparison with Hadrian’s Panhellenion as another institutionalised confederation which united Greek cities and fostered an ethno-cultural definition of Greekness in the 2nd c. AD.