School development has traditionally been synonymous with teacher development. Teachers have been seen as the centre about which the school rotates, and the school was the sum of its individual teachers. To a large extend, it still is so, but the conditions for school activities have changed dramatically, both the general framing and the work in the classroom - and the relation between the two (Hargreaves 1994)! For teachers the work with the students has always been the core purpose, and meetings, discussions of statement of aims etc. have been regarded as taking time from the essential: the teacher's own time with his or her own students working with the subject. As schools are more and more considered organisations and tools for strategic goals formulated on regional and national levels, the teachers feel themselves caught in a cross-pressure between their everyday job and the demands coming from the organisation and the outside. The way teachers conceptualise and react on this situation constitutes potentials and barriers for school development (Hoban 2002). Four high schools (year 10-12, "the gymnasium") in different parts of Denmark have been investigated within an extensive research project "Potentials and barriers for school development". The schools have been selected among high schools with a development programme involving the whole school. The investigation includes a questionnaire completed by all teachers and the school management (192 persons), interviews with representative teachers (18) and the management (12), plus interpretation of school documents. The material has been analyzed on four levels: A teacher level, a team level, a staff level, and a whole school organizational level. The interviews have been analyzed using a grounded theory approach, and pieced together with the results from the questionnaire and the documents to give a picture of the barriers and potential for school development on each level. This presentation will concentrate on the teacher level, with perspectives to the other levels. Condensation of the teachers' utterances about relations between the individual teacher, the teacher's subject, and the organisational development programme, revealed the following categories: attitudes towards the subject and pedagogy, a meaningful job, ownership of the project, relations to the management, working conditions, philosophy of life. These categories will be examined to get a picture of the variety of teacher thinking within each of the groupings. The results will be related to the more quantitative findings from the questionnaire. Different kinds of educational intervention, such as team teaching, project work etc., were for instance correlated to changes in teachers' conception of teaching and of the subject. The feeling of ownership to the project was correlated to the engagement in and sense of usefulness of the project, etc. The conclusion will be interpreted in the theoretical frame of Communities of Practice (Wenger 1998) in order to show how an organisational development is dependent on the forming and development of communities of teachers. The Danish gymnasium is facing a major reform in 2005 - named the greatest reform in 100 year - and the results from the research project are relevant for the teacher and management training preparing the teachers and the management for this reform. Some suggestions for improving teacher and leader training will be presented. Literature Andy Hargreaves: Changing Teachers, Changing Times: Teachers' Work and Culture in the Postmodern Age. Teachers College Press 1994. Garry F. Hoban: Teacher learning for educational change. Open University Press 2002. Etienne Wenger: Communities of Practice. Learning, Meaning, and Identity. Cambridge University Press 1998.