This article offers a new interpretation of the Athenian institution of ostracism and explores its significance for our understanding of democratic politics. A popular scholarly trend interprets ostracism as an instrument for pursuing (or regulating) conflict among aristocratic politicians, in accordance with a view of Athenian democracy as dominated by a restricted elite competing for power and prestige. This article aims to reassess this picture by investigating ostracism in the light of recent studies of honour, which have stressed honour's potential for balancing competition and cooperation within communities. By using the ostracism of Themistocles as a case study, it argues that ostracism was a manifestation of an institutionalized concern for honour in Athenian democracy. On the one hand, ostracism could punish politically active citizens who, in excessively enhancing their own honour, failed to respect democratic equality. On the other, it could be employed for tackling shameful behaviour which placed the agent below the community's standards of honour. The article then sets ostracism against Athens’ broader institutional framework and argues that Athenian democracy was not so much concerned with policing intra-elite conflict as much as it was designed to foster a balance between competitive and cooperative values and ensure broad participation in the political domain.