Ćićarija with its characteristic imbricate and thrust structure is one of the most geologically and tectonically complex areas of Croatia. Ćićarija stretches along the NE margin of the Istrian peninsula, and along its SW margin it is morphologically uplifted above the surrounding terrain. The main objectives of this doctoral thesis were to investigate the geological architecture and reconstruct tectonic movements that will explain the kinematics of the structures formed in the study area by conducting a detailed structural analysis of the collected field data. As a part of this research a new detailed geological map based on lithostratigraphic principles has been produced. More than 220 km2 of the mapped area include the central part of the Ćićarija and marginal area of the Pazin flysch basin. Geological map comprises 13 informal lithostratigraphic units named after units already defined in other areas of the Karst Dinarides. A very important new scientific contribution of the new geological map is more detailed stratigraphical discussion of Cretaceous units. Detailed reconstruction of the Ćićarija and western Istria paleogeography was made on the basis of a well-defined vertical and lateral sequence of deposits of different lithostratigraphic units within the investigated area and detailed comparison with penecontemporaneous lithostratigraphic units of the wider area of Istria and other parts of the former Adriatic Carbonate Platform. On the basis of the geological map 11 transverse geological cross-sections of the investigated area have been constructed. Geological cross-sections show the interpretation of subsurface relationships of structures based on surface data. The Palaeogene imbricated structure was formed as a result of compression and thrusting of northeastern hinterland composed of Cretaceous and Palaeogene deposits causing significant contraction of the area. It may be concluded that the Palaeogene imbricated structure of the SW part of the Ćićarija represents a thin-skinned deformation of exclusively Palaeogene deposits that are physically separated from the underlying Cretaceous basement by a shallow regional-scale detachment fault dipping towards the NE at a very low angle. Lowermost part of the Foraminiferal limestones, i.e. Miliolid limestones, which contain a substantial bituminous content are suitable for the development of shear planes, and they are proposed as possible décollement surface. The thrust contact of Palaeogene imbricated structure and Cretaceous deposits is of a low angle and mostly dipping towards the NE, while tectonic transport for mapped nappes and imbricated structures is SW-directed. In the area of the Palaeogene imbricated structure reverse faulting of the Palaeogene deposits package show the ramp and flat geometry. Within the imbricated structure system, as a detachment horizons are proposed marls from Transitional Deposits, and very rarely marls from the lowermost part of the Flysch sequence. The investigated area is divided into six local structural-tectonic units according to the differences in their lithostratigraphic properties and structural characteristics. These units are separated by major reverse and thrust faults of regional significance. Boundary faults and most important folded structures within structural-tectonic units are named after local toponymes. For determination of fault kinematics in relation to the past and present stress fields, here, data of field measurements of dip directions and dip angles of fault planes and orientation of carbonate slickensides, as well as their sense of movement were used. Based on kinematic criteria, the structural data were separated into compatible datasets and processed by appropriate softwares (Stereonet, FaultKinWin, Win-Tensor and TectonicsFP). By using the P–T axis method theoretical maximum (σ1), intermediate (σ2) and minimum stress axes (σ3) have been calculated. Additionally, using the Right Dihedra Method, synthetic focal mechanisms for the analysed fault segments, i.e., palaeo-synthetic focal mechanisms as representations of the palaeostress fields were determined. On the basis of the structural data measured in the field and the results of kinematic analysis two major tectonic cycles were defined in the study area. The older cycle, refer to Palaeogene Tectonic Cycle that is characterized by compressional palaeostress field with the P-axis dominantly trending NE‒SW. This tectonic cycle formed structures of the NW‒SE strike direction, i.e. the Dinaridic strike. The activity of the younger, Neotectonic Tectonic Cycle in the study area began probably during the Late Miocene and/or Pliocene, and continues to recent. This tectonic cycle is characterized by compressional/transpressional stress field with N(-NE)‒S(-SW) oriented P-axis. Neotectonic activity resulted in newly formed structures, striking N(-NE)‒S(-SW), with sporadic deviations to the NW-SE strike, and structural reactivation of the older Dinaridic strike faults resulting in a dextral/sinistral movements. These results are correlatable with the description of both tectonic cycles in the wider area of NW Dinarides. Interpretation of structural-tectonic relationships as well as analysis of the paleogeography of the study area through the Cretaceous and Palaeogene contributed to the knowledge on the tectogenesis of the present structural architecture.