In the two decades since the emergence of the European Union with the Maastricht treaty there has been a concerted attempt to build a European political space,typified by the debates on constitutionalisation and democratisation. Much less noticed, but no less important, has been the mobilisation of publics, interest groups andpolitical parties against the integration process. In the light of the failure to realise the Laeken objectives, the stabilisation of an anti-integration bloc in the EuropeanParliament, the recurrent 'no' votes in national referenda and the emergence of an increasingly coordinated movement of critical interest groups, we would argue thatthis opposition has become embedded and persistent, at both European and national levels. Moreover, it requires an understanding of the label of 'euroscepticism' thatrecognises its relationship with different degrees of opposition, constructive criticism and conditional support of the European integration process. This will haveconsiderable consequences for the Union itself and the way it has chosen to largely ignore sceptical voices to date.