Although the Court of Justice stated in one of its judgments that Union citizenship was not supposed to extend the scope of EU law, the opposite has happened. This chapter investigates the interaction between EU citizenship and the scope of EU law. It begins with an overview of the purely internal situation rule that mandates the presence of a cross-border element for EU law to be applicable. The chapter then looks into how Union citizenship challenges this rule and makes it possible to apply EU law to situations that are confined to one Member State. After that, the chapter turns to the phenomenon of reverse discrimination. After providing a short overview of it and looking into possible exceptions, the chapter focuses on how the concept of Union citizenship goes at loggerheads with reverse discrimination.