Educational arenas are important sites for understanding how diversity and democracy become operationalised since they constitute and at the same time must attend to students' different needs. This article focuses on diversity from two specific angles: how research activities allow for particular ways of understanding human differences and how human pluralism is conceptualised in the organisation of education. These discussions emerge from the position that our use of language itself shapes human realities. The organisation of the segregated Swedish special schools for the deaf and research that focuses on this specific "human category" are used to illustrate and discuss issues pertaining to diversity and democracy. Pupils in special schools are conceptualised both as "handicapped" as well as belonging to a "linguistic-minority" group. Democratic tensions related to maintaining a separate school and conducting research on the human category defined on the basis of "deafness" are discussed and alternatives raised. Implications regarding (the lack of) pluralism in research perspectives and agendas are also discussed and the need for integrating studies of marginalisation into mainstream academia is highlighted. (Contains 15 notes.)