Triglav National Park is the only national park (NP) in Slovenia. Its protection measures have always been publicly disputed and its impact questioned. This paper identifies and assesses the impact of the park on regional development. It compares two kinds of data: the municipal development coefficient based on statistical data and residents' attitudes toward the park, based on analysis of a survey, newspapers, and public debates. Triglav NP is located in two regions: Goriška and Gorenjska. Our results show that the municipalities in Gorenjska are better developed; however, the development trends in these municipalities are decreasing, whereas in the Goriška region they are increasing, overall reducing the regional differences between the two parts of the park. Text analyses reveal that lack of clarity in the management, boundaries and funding of the park, as well as inconsistency with existing legislation and international standards, have resulted in constant conflicts, which have impeded regional development. We argue that, once the conflicts are solved and local communities perceive positive changes as a result of implementing the law, progressive effects developing the protected area will follow. Triglav NP has the potential for long-term positive impacts on regional development if there is sound legislation, if this legislation is effectively implemented and if an active participatory process is put in place.