In this thesis, we focus on the development of the urban system in Slovenia. The topic is important in terms of spatial arrangements and the settlement, as it represents a network of cities and settlement and their interactions, with regard to the hierarchy of cities and settlements of various sizes and functions. In the first part of work, theoretical part, we define the topic based on existing literature, presents the established definitions of urban system and its components; present a well-established theory of central places and the concept of polycentricity. In the second part of work, we use milestones in history, an overview of studies, adopted spatial planning legislation and adopted strategies to present the development of a polycentric urban system and the design of settlements in Slovenia since the end of the 2nd World War. With the analysis and critical assessment of the development of the urban system and an analysis of progress in the development of the urban system in Slovenia, we present a conformity assessment of the development of a polycentric settlement concept, according to the objectives, which were set in the adopted legislation and the adopted strategies. In this part of work, we try to give an answer to the question of whether the objectives to develop a polycentric urban network, installed in the past were met. We also try to determine whether the development of polycentric urban system is going in ambitious direction and we try to find places, which have been, are and will be the frame of polycentric urban system.