Book excerpt: The question of supranational citizenship is one of the more controversial in EU law. It is politically contested, the object of prominent court rulings and the subject of intense academic debates. This important new collection 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 not only timely but essential given the prominence of citizen rights in recent political debates, including in the Brexit referendum. All of these questions will be explored with a special emphasis on the interplay between immigration from third countries and rules on Union citizenship.