This thesis examines constraints of the EU’s engagement in the frozen conflicts of the South Caucasus, namely, the Abkhazia, the South Ossetia, and the Nagorno-Karabakh conflicts. The study begins with a puzzle in which the EU’s ambition for prioritizing the resolution of frozen conflicts mismatches with the reality related to the status quo of frozen conflicts. By using an abductive reasoning in an observed surprising fact, the research highlights that the complexity of the region can be the main contributor to the EU’s limitations.   With this purpose, the ENP as a normative power of the EU is analyzed to identify how the EU is attempting to be a major actor in the region in order to secure its borders. Subsequently, the limitations of the EU in engaging in frozen conflicts are examined from ‘security dilemma’, ‘balance of power’ and ‘bandwagoning’ neorealism perspectives together with a comparative study on the three conflicts. The results show that the complexity of the region is a principal constraint for the EU. In particular, geopolitical rivalries with Russia and small states with their alliances contribute to the complexity of the region. However, this study also explores the idea that the complexity of the region is not only the best explanation for the EU’s limitations, but also the EU’s structure per se creates a lack of credibility with relations to the respective Caucasian states. For future studies, I suggest that the analysis of the social learning mechanism of the EU will be an asset for understanding the region and avoiding Eurocentric approaches towards Caucasian political systems and people. Regarding the Nagorno-Karabakh conflict, policymakers can consider that it is possible to change the EU’s low profile either by having clear strategies concerning the Nagorno-Karabakh conflict or replacing one of the co-chairs of the OSCE Minsk Group with the EU.