The present theoretical thesis seeks to elucidate how pre-existing theoretical perspec- tives and empirical research account for nature’s impact on psychological well-being. Psychological well-being is understood based on Carol Ryff’s multifaceted and com- plex concept associated with eudaimonic aspects of optimal human development and flourish. Based on a critical realist approach theoretical perspective were critically and carefully selected to elucidate on the research aim on the three ontological layer in order to attain a comprehensive understanding of nature’s impact on psychological well-being. Initially, the human-nature relationship was elaborated on from different historical perspectives including an evolutionary approach, ecopsychology, environ- mental psychology and Cronon’s critical approach. These constitute the foundation of the following theoretical examination. In this section environmentally focused theories were found to account for biological, cognitive and developmental aspects of nature’s psychological benefits. Despite limitations in their explanatory abilities due to simple essentialist explanations. To further explore these limitations, subjective aspects of ecopsychology were examined, including nature connectedness and transpersonal di- mensions. An important missing account on positive-negative implication in psycho- logical well-being were identified through the review of the literature and showed sig- nificance in further understand nature impact on psychological well-being. Through a final discussion of different conceptualizations of respectively psychological well-be- ing and nature, important ontological and epistemological implications were identified and following discussed. The relationship between nature and human psychological well-being is a nuanced field that calls for more than one level of understanding and approach of interpretation. In conclusion nature seems to involve experiences of cog- nitive restoration and stress recovery. On the other hand the encounter with nature also involve a deep sensory, embodied, emotional and spiritual experiences deepening the subjective connection between human and nature. A connection that facilitates overall psychological well-being. Finally, nature can be understood as a socially constructed phenomenon, in which societal, cultural, economic and subjective aspects play an im- portant role in how nature is perceived and experienced, how individuals prefer nature differently, but also how some people have limited access to nature. All these aspects have an impact on how we can understand the impact that nature has on psychological well-being.