Slovakia’s accession to the European Union (EU) in 2004 was not a simple road. The process by which the country fulfilled the Copenhagen criteria rather saw its share of ups and downs, with significant progress made possible through structural financial assistance from the EU’s pre-assistance mechanism. This chapter examines the role of financial instruments in the implementation of the European Association Agreement regarding Slovakia, the transition of the economy, the construction of a democratic and stable political environment facilitating the achievement of enlargement criteria, and efforts to enhance the country’s social transformation. The historical content analysis of this legal, political, and economic development assesses the impact of pre-accession assistance and identifies promising practices to inspire other candidates en route to the European Union. It also underscores challenges in the process, with a focus on identifying necessary mitigation measures. With the accession of Slovakia to the European Union, the ongoing process of financial support has been transformed into cohesion and social policy. Therefore, the aim of this research is also to highlight the sustainability of financial support post-accession and the ways in which Slovakia has continued to meet the objectives and apply the policies established before accession to the EU.