This study aims to examine a well-known inscription (IG XII.5, 225) dated to the mid-fifth century BC and found in Paroikia, near the acropolis of the ancient polis of Paros. It shows a typical formula of access limitation to local cults: according to most scholars, the cult in question is to be identified with the worship of Kore Astos (the Citizen), who is mentioned in the second line. The Dorians are excluded from this cult, as is shown by the expression (xenoi Dorie) appearing at the beginning of the text in a very relevant position. On the basis of a close comparison between this text and other epigraphs as well as literary documents containing proscriptions which prevent foreigners from participating in cults, it can be concluded that our text offers the only known example of such a limitation pertaining a specific ethnos. The reason for this rule established in Paros lies in the background of the Pentecontaetia, when political relations between Athens and its allies against the Dorians were bolstered not only politically, but also through cultual practices. Kore was a pivotal deity in strengthening the sense of sharing cultural traits in both Parioi and Athenians; perhaps it is for this reason that those people who did not belong to the Ionian ethnos (the Dorians first) were excluded from this cult.