Naturalness is widely used to assess the conservation value of forest ecosystems. As this concept encompasses ecological as well as sociological aspects, we adopted an inter-disciplinary approach to study naturalness in two Chartreuse forests (one managed and one unmanaged). The aim was to know whether differences between the two forests assessed through measured ecological indicators, including stand characteristics, and public perception converged. We translated scientific language into more easily accessible terms, then interviewed 30 visitors in each forest. Many ecological and sociological perceptions did converge, notably in terms of criteria of composition, structure and function. However, more specifically, some scientific terms could not be fully transposed and some indicators of naturalness diverged between scientists and general public. The general public seems to be able to differentiate between degrees of naturalness, but studies as the one conducted here need also more influence of sociology on ecology to be fully interdisciplinary. Involving the general public in forest conservation issues could enhance understanding and avoid potential conflict.