The social impacts of Protected Areas (PAs) are increasingly recognized as a key issue that needs to be explored and combined with existing evaluation frameworks assessing the economic and environmental impacts of PAs. The present paper focuses on the subjective assessment of social impacts of PAs and how these perceptions are formulated. Results of an empirical study, implemented in three PAs in Greece, are presented. According to the study, individuals' perceived quality of life, trust in institutions, social trust and place attachment are the most important indicators influencing perceptions of social impacts. A main conclusion of the paper is that measuring social impacts is not sufficient for the planning and designation of a PA. Additional research is needed exploring the reasons behind these perceptions in order to plan actions minimizing negative impacts for local communities.