In this chapter we examine the understanding of naturalness in the doctrines of the “forest actors” and how this understanding influences the working practices of the respective actors in the context of climate change. Methodologically, this article is based on qualitative interviews with private and public forest owners, with foresters, scientists and administrative actors in France and Germany. This allows to clarify the importance of naturalness in forest management doctrines and practices in Germany and France. In addition, we show how the different actors’ understandings of naturalness influence the forest management. The analysis of the interviews shows that a number of recurring issues highlight the challenges faced by the different forest actors. The analysis itself endeavours to show how the understanding of naturalness affects these various key issues such as the choice of tree species, the management of forest pests and the question of the nature conservation approach.