How can we develop students' ability to argue about diversity? Sarah Black explores this question through classroom research that set out to help students think in complex ways about diversity, drawing on Burbules' work on conceptualising difference and diversity. Black's study explores the difficulties that students face when trying to develop sophisticated arguments about this complex topic and compares students' ability to argue verbally and dialogically and their ability to argue monologically and in writing, noting ways in which students struggle to sustain levels of sophistication that they can achieve in verbal argument when they come to develop arguments in writing. (Contains 17 figures.)