The chapter in a new Oxford University Press encyclopaedia offers an all-encompassing literature review of Slovenian EU-engagement from the Yugoslav times up until today. It provides an analysis of sources from the fields of Political Science, European Studies, International Relations, Economics, Diplomacy, and Development studies. The authors critically evaluate where and why during the effort of becoming an EU member state and performing excellently as one during the first four years, the state fell short of capability-building and/or seizing the opportunities of EU membership. They also refer to the most recent challenges of the state within the EU and of the EU as a whole.