This thesis explores the development of European Union’s model of protecting its citizens in the world, demonstrating it to be a unique and complex mixture of EU internal and external policies and instruments that is unlike any other international, regional, or domestic model of protecting individuals abroad. The thesis will critically assess the three main stages of development of the EU model until the present day. The first stage started in 1993, when the Maastricht Treaty introduced an EU citizenship right to equal protection abroad and this continued for the following decade. It will be shown that during this period the EU model of protecting the Union citizens abroad consisted of a purely horizontal form of cooperation among the Member States that materialised in a sui generis type of international agreement that has restricted the efficiency of the EU citizenship right, due to the Member States’ reluctance to lose their State prerogatives in favour of the EU. The second stage of development started in 2004 when a number of international disasters affecting EU citizens in third countries led the Member States to accept cooperation with EU institutions and external policy instruments for the purpose of complementing their capacity to secure the effective protection of unrepresented Union citizens abroad. The third stage started with the entry into force of the Lisbon Treaty, which conferred an unprecedented power to an international organisation (the EU) to exercise State-like consular protection functions directly with respect to the Union citizens in the world. The thesis will offer a critical assessment of two decades of application of the least-researched EU citizenship right (to consular and diplomatic protection), its nexus with other EU external relations policies and its implementation by the Member States. It will show the added value of the EU model of protecting citizens abroad for the EU citizens, the Member States and the Union, while also making policy recommendations addressing the shortcomings in its current implementation. The thesis will demonstrate that, in spite of the scholarly critiques of the incompatibility of the Union model with public international law, the international community has widely accepted.