Classroom discussion is frequently proposes as an essential part of democratic citizenship education. Literature, however, pays little attention to what kind of discussion is most effective and how teachers can facilitate a discussion. This study aims to contribute to the development of a framework for analysing the characteristics of classroom discussions and the different roles teachers can adopt in guiding a discussion on controversial issues. In addition, we investigated how the way teachers guide the discussion is related to the structure and content features of the discussion. The framework was used to analyse five classroom discussions in secondary education. Our framework appeared to be useful for revealing differences in the structure and content features of the classroom discussions and in the way teachers guide the discussion. The results also indicated that a high degree of teacher regulation was related to high content quality and more participation from students. A high degree of student regulation was linked to more genuine discussion among students. The study underlines the importance of taking account of the teacher's role in research into the effectiveness of classroom discussions for democratic citizenship education and the study makes useful suggestions for teachers when preparing for a classroom discussion.