This report summarises the work carried out in the last two years of a four-year project funded by Nordic Council of Ministers. The objective of the project was to develop concepts and methods for assessment of nature quality in selected habitat types.The motivation for the project lies in increasing societal demands for information on the state of our natural environment and especially the state of our biodiversity has attracted increased attention over the last decades.The project have explored the normative concepts of conservation, and found that consensus about objectives are needed before numerical methods for quality assessments can be developed. In this project naturalness has been adopted as the overall conservation objective, and it is described how this concept is related to other concepts in conservation biology. The criteria for conservation as they have been used in the Nordic countries till now have also been reviewed.