A structured controversy approach to teaching in environmental education is evaluated. Learning experiences which challenge and enhance students' conceptions of environmental issues and environmental education by confronting them with alternative viewpoints and evidence were trialled in two postgraduate environmental teacher education courses. Findings indicate that as a result of participating in the learning experiences, students formulated their own position more clearly, better understood the viewpoints of others, became aware of inadequacies and inconsistencies in their conceptions and were challenged to increase their environmental commitment. They were able to explore the strengths and weaknesses of different teaching approaches in environmental education and develop and justify their own preferred strategy. Most students responded favourably to the use of controversy and valued the peer discussion and conceptual challenge it evoked. Further development of this technique in enhancing student environmental conceptions across a range of relevant disciplines is recommended.