Supranational citizenship is controversial: it is politically contested, the object of prominent court rulings and the subject of intense academic debates. A collection with prominent authors from across Europe, which was published with Bloomsbury/Hart, examines this vexed question, paying particular attention to the Court of Justice. Offering analytical readings of the key cases, it also examines those political, social and normative factors which influence the evolution of citizens‘ rights. This examination is essential given the prominence of citizen rights in recent political debates, including in the Brexit referendum. They are explored with a special emphasis on the interplay between immigration from third countries and rules on Union citizenship.