This article argues that obligatory, simultaneous, and simple Treaty ratification by referenda is the next step in the consolidation of the political core of European citizenship. In the first part, general remarks about the special nature of EU citizenship highlight the relevance of referenda on EU Treaties for EU citizenship. In the second part, the normative and empirical case in favour of direct democracy is put forward. It is followed by the assessment of direct democracy in European integration as we have known it so far. The practice is irreversible and gaining in momentum. But it is in need of substantial reform due to procedural dysfunctions and discriminatory consequences for the citizens. Section V relates this result to a legal analysis of EU citizenship. The suppression of the discriminatory consequences of the Treaty ratification procedure is necessary from a legal point of view, but it cannot be expected from the 'judicial incrementalism' that has characterised the development of EU citizenship regarding free movement and residence. In section VI, the conclusions of the previous sections are drawn into the final proposal of obligatory, simultaneous and simple Treaty reform by referenda in all Member States. At the end, five counter-arguments to the proposal are discussed.