The purpose of this study is to comprehensively analyze the role, purpose, and functioning of the European Union institutions, specifically the European Social Fund, concerning the effectiveness of the European social policy system in implementing measures to combat poverty in the Republic of Croatia. The European Union represents a unique political entity comprising member states with shared economic, sociological, and geopolitical interests. The Union possesses an autonomous legal system that is unparalleled in comparison to any other international legal framework, thereby reflecting its political and legal distinctiveness. The European Union operates through its key political institutions and bodies, with the European Council being one of the pivotal bodies responsible for determining general political guidelines and major priorities. These political directives from the European Council are mirrored in the activities of institutions such as the Council of the European Union, the European Parliament, the European Commission, and member states. The European Social Fund (ESF), as one of the structural and investment funds within the European Union (EU), serves as a significant source of funding for civil society organizations dedicated to investing in human resources and promoting the well-being of EU citizens. In the Republic of Croatia, the fight against poverty represents a substantial challenge that is accompanied by various complexities, which competent institutions endeavor to address.