Theoretical background: Studies on teaching strategies in daily tense situations in schools show that many moral dilemma's that teachers experience, remain unsolved (Husu, 2002; Tirri and Husu, 2002; Husu and Tirri, 2001; Maslovaty, 2000). Empirical research on teachers' professionalism in ethnically diverse classrooms is scarce. The few Dutch empirical studies that have been carried out on teachers' experiences with teaching ethnically diverse classrooms point out that teachers report new professional questions and problems (Leeman and Ledoux, 2003; Leeman, 2003). These studies are qualitative studies with a small sample. In order to provide an overall picture of questions and problems teachers' experience in ethnically diverse classrooms, we conducted a survey study among teachers and pupils. The results show that tense situations are part of daily life at ethnically diverse schools. Teachers attribute a relatively large role to ethnic cultural differences to most situations they experience as tense. An image of insecure teachers appears from the results, since (on average) one third of the teachers indicate they face difficulties concerning the decision which strategy to apply to these situations. Teachers chose to have a discussion as a response to most tense situations that occur. Building on these results, we conducted a qualitative study that is aimed to give in depth voice to teachers' experiences with this specific teaching strategy for managing tense situations. Research question: This paper aims to provide insight into the demands that teaching in an ethnically diverse classroom poses on teachers' professionalism. The focus is on teachers' experiences with leading a classroom discussion on difficult issues in ethnically diverse classrooms. Do teachers feel sufficiently capable? What considerations they have regarding the way a classroom discussion should be structured? And how do they structure these discussions? Research method: The present study is situated in five ethnically diverse classrooms of schools of the vocational track in secondary education. The selected schools are situated in Amsterdam. The data collection for this study consists of interviews and classroom observations. Teachers have been asked to lead a discussion in their classroom about an issue of which it is likely that pupils' opinions differ. In preparation to the classroom discussion, we showed the teachers three short video-excerpts that consist of scenes at which pupils are involved in a fierce talk on a specific issue, for example freedom of speech. We asked the teachers which excerpt they would choose to discuss in their classroom, and for what reason. Next, we asked them to reflect on the way they would structure the discussion and which problems or questions they expect to be raised during the discussion. The classroom discussions, based on the chosen video-excerpt, took place within two weeks after the interview. These classroom discussions have been observed. Results: The data-collection of this study started in autumn 2004 and will continue until spring 2005. The analyses of the interviews and observations will be focused on shedding light on teachers' professionalism in ethnically diverse classrooms, based on their experiences with and reflections on classroom discussions about difficult issues. Building on these results, we aim to suggest some requirements regarding teachers' professionalism in ethnically diverse classrooms. References Husu, J. (2002). Representing the practice of teachers' pedagogical knowing. Turku: Finnish Educational Research Association. Husu, J. and K. Tirri (2001) Teachers' ethical choices in sociomoral settings. Journal of Moral Education 30(4): 361- 376 Leeman, Y.A.M. (2003). De pedagogische opdracht in een multi-etnische context: docentendilemma's. [The pedagogical task in a multi-ethnic context: teachers' dilemma's]. Pedagogische Studiën 80 (6): 468-484. Leeman, Y. and G. Ledoux (2003). Preparing teachers for intercultural education. Teaching Education 14(3): 279-291. Maslovaty, N. (2000). Teachers' choice of teaching strategies for dealing with socio-moral dilemmas in the elementary school. Journal of Moral Education 29(4): 429- 444 Tirri, K. and J. Husu (2002). Care and responsibility in 'The best interest of the child': relational voices of ethical dilemmas in teaching. Teachers and Teaching: theory and practice 8 (1): 65-80