This article takes a closer look at the legal framework on citizenship of the Union. In particular, it analyzes the amendments that took effect at the end of 2009, due to the entry into force of the Lisbon Treaty. Though at first sight, these seem to verge on the trivial, the present paper engages in detailed scrutiny, and hypothesizes that a more fundamental change may be perceived than is commonly acknowledged. It attempts to map the consequences of this supposed watershed with regard to both EU and third country nationals. Ultimately, it argues that the novel place attributed to the concept extends its reach further than ever before, and supplies it with a massive potential that the European Court of Justice is poised to exploit.