This collection of research is the result of fruitful collaboration between the Department of Geography of the University of Zagreb in Croatia, and the Department of Geography of the University of Primorska in Slovenia, which was implemented within the framework of a bilateral research project entitled “Comparative Analysis of Spatial Development of Tourism in Protected Areas of Croatia and Slovenia”, in 2018 and 2019. The main objective was to perform a comparative analysis of the spatial development of tourism in protected areas in Croatia and Slovenia. In order to achieve this goal, the authors of the chapters studied several examples of tourism development in protected areas in both countries.