The national system of management and implementation of the European Union (hereinafter: EU) cohesion (hereinafter: regional) policy, its manner of functioning, its adjustment and, consequently, the effectiveness of this system, has a decisive influence on the dynamics and expediency of drawing from EU regional policy funds. Considering the relevance of this topic due to the end of the European budgetary period 2014-2020, and the perspective of the new budgetary period (2021-2027), this doctoral thesis rises above the time limits of budget periods because it analyses the use of EU regional policy funds in the context of scientific contribution to a draft model of the institutional framework for managing EU regional policy instruments (funds) in Croatia. In this context, one of the biggest problems and challenges is the fact that Croatia was the last to become an EU member country and at the same time the only one that uses EU regional policy funds for only one budgetary period. Therefore, it is an additional challenge to gather enough empirical and econometric knowledge about the functioning of the EU regional policy funds management system in selected EU countries, for the conclusions to apply to Croatia. Special attention was paid to the presentation of the EU regional policy funds management systems in countries with similar characteristics comparative to Croatia, through empirical knowledge and laws, modern approaches and theories that contribute to solving current, complex, theoretical and practical problems, which have not been sufficiently researched or present in the national research area. The results of the organizational and efficiency analyses of the EU funds management system in selected countries are the focus of the research conducted within this doctoral thesis. Scientific research served as the basis for providing guidelines for defining the optimal model of the EU regional policy funds management system in Croatia, which, by the time of this analysis, due to its low efficiency, the complexity of the decision-making system and a kind of "intertwining" of institutions in the process of preparation and implementation, has failed to maximize the utilization of EU regional policy funds. To be able to empirically determine the key institutional factors for the EU funds absorption from the existing management systems of selected EU countries, the existing management systems are considered. Through scientific research and comparative analysis of the EU regional funds management system in nine Central and Eastern European countries, along with the experiences of the Croatian system, this paper aims to determine an optimal framework for a national EU regional policy fund management system that would enable the executive power to adopt better strategic decisions. The abovementioned framework should, to the greatest extent possible, stimulate economic growth through the efficient use of EU regional policy funds. The results of the conducted econometric analysis contribute to the conclusions confirming that the received EU grants have led to an increase in the economic development of EU countries. However, the allocation of funds alone did not necessarily lead to an increase in the quality of the institutional environment and the competitiveness of the countries analysed. Furthermore, it is confirmed that an institutional framework for the management of EU funds should be established, which will not only increase the absorption of EU funds but will also improve the overall efficiency of the public sector and the competitiveness of the state. Therefore, this doctoral thesis, based on systematic and comprehensive scientific research, proposes and asserts a model of an institutional system for management and implementation of instruments (funds) of EU regional policy in Croatia that is applicable in the short and long term.