During the Decade of Education for Sustainable Development, DESD different implementation activities are common in countries worldwide where one interesting question is – what happens in a school when sustainability issues are implemented? This paper is a part of larger Swedish research project which aim to study norm-development in ESD-schools. This is an empirical study of data from interviews of eleven upper secondary teachers working in three ESD-schools. An analytical tool, developed in earlier research with starting point in the philosophy of Dewey and Wittgenstein, is applied on data to answer the research question: What do teachers really care about when they argue for their teaching approach related to sustainable development? In teachers long term purposes from two experienced ESD-school it is possible to discern some interesting commonalities. In general, these teachers are concerned about how their subject/discipline supports students’ abilities to handle and increase learning from the complexity of sustainable development. The role of the educational content in these complex subject integrated issues is crucial for teachers to discern and better understand. The implications of teachers’ purposes beyond the actual teaching are important for all stakeholders interested in the implementation of ESD issues in schools to be aware of.