European integration and enlargement are one of the key aspects in the functioning of the European Union. They refer to the process of political, economic, and social unification of European countries, aiming to enhance cooperation and prevent conflicts in a region with a turbulent history. This endeavor has historically led to the establishment of various institutions, most notably the European Union, which facilitates collaboration among its member states in numerous areas, including trade, security, and environmental policy. Serbia, as a part of the Western Balkans, has been pursuing EU membership since the early 2000s, amidst a complex regional landscape marked by historical tensions and socio-political challenges. Serbia officially applied for EU membership in 2009, and in 2012, the European Council granted Serbia candidate status. The integration process for Serbia is influenced by several factors, including the normalization of relations with Kosovo, which declared independence from Serbia in 2008. The EU has emphasized the importance of dialogue between Serbia and Kosovo as crucial for Serbia's accession aspirations. The path to EU membership for Serbia involves fulfilling the rigorous Copenhagen criteria, which include political stability, a functioning market economy, adherence to the rule of law, and respect for human rights. Serbia has made significant progress in adopting EU legislation and reforms, especially in judicial independence, anti-corruption measures, and strengthening democratic institutions. However, challenges remain, particularly in relation to political polarization, economic development, and ongoing regional relations. This master’s thesis aims to identify and describe the challenges of successful enlargement and integration of countries and their political, economic, social and legal systems, by analyzing the case of Serbia and its negotiations regarding joining the European Union.