Cohesion Policy is one of the most important policies implemented in the European Union. This policy has changed over time, according to the needs of integration and its regions. The aim of this thesis is to present development of the Cohesion policy in the European Union with more detailed analysis of the planned changes in the future programming period, 2021-2027. At the beginning of this work, the idea of cohesion and the main characteristics of the Cohesion policy are presented, especially in the programming periods 2007-2013, 2014-2020. Funds are described as the main instruments of the policy implementation. After that follows a section on the effects of the Cohesion policy that encompasses summary of reforms, presentation of regional differences and achievements of the policy. The next section describes the reforms planned in 2021-2027 and in more detail the main changes. In the last chapter the main advantages of Cohesion policy in Croatia are also highlighted. This work confirms positive effects of Cohesion policy, but also the needs to change some directions for better performances. Analysis of the planned changes in the next programming period has shown that contributions from previous periods are retained, while there is a need to modernise some actions, adjust the policy on new constraints and to achieve simpler, more flexible implementation. New guidelines for the next Cohesion policy should contribute to smarter, greener, more connected Europe, more social Europe and Europe closed to citizens. Also, in this new framework, Croatia needs to be more successful and to accommodate on time for planned changes.