The chief cause of success or the reverse in all matters is politeia ; for springing from this, as from a fountainhead, all designs and plans of action not only originate, but reach their consummation. Polybius - The Histories, c.150 BC Inspired by Pocock's Machiavellian Moment , 1 the title of this article is a phrase to be interpreted in two ways. On the one hand, it depicts a particular 'moment' in the evolution of the European Union (EU) as an ordered 'sympolity' of states and demoi , where republican theory emerges as a conceptual and analytic form of scholarly inquiry into the EU's puzzling ontology. In that regard, republican conceptions of Europe form part of an ongoing research programme bringing into focus the uses of normative theory in EU polity-building. On the other hand, the title denotes a specific moment in the setting of the EU's public agenda, where questions of polity, democracy and good governance increasingly inform the search for a socially legitimised EU political system. In combining these two ways of interpreting 'Europe's Republican Moment,' this article aims to link republican political thought with the new conceptual and democratic challenges facing EU scholarship, with a view to sketching a clearer picture as to which direction the 'political constitution' of Europe should take.