This work is a study of subject teachers in social studies and science understand the concept of sustainable development. The work uses a qualitative and a quantitative approach. Teachers in various schools and stages have been answering questions about how they perceive sustainability, how they implement it in teaching and if they feel that school is important for the future of sustainable development at large.The theoretical background is based on environmental ethics as well as the different meanings and definitions of the concept of sustainable development. These theories and definitions are coupled with the empirical results.The study concludes that all teachers throughout the study perceive the concept of sustainable development as something ecological, something that has to do with nature. A few teachers also state economic and social dimensions.Questions about how the teachers in the study implement the concept in their teaching can be seen as three different approaches.