In this article Copeland's model of visualising the classification of children with learning disabilities is applied in examining the development of special education schools in the Netherlands during the interwar period. Central are three intertwined social practices: the teacher's professionalism (in pedagogic and practical concerns), the expert's knowledge (in theory, research and practical advice) and the pillarised social structure that is typical in the Dutch case. Moreover, gender is added as a central category because of its crucial intermediating role in the Dutch developments. In order to understand the interaction between these practices and the denominational structure, the professional identity of male and female teachers in special education classes and schools is studied in relation to the religious stratification within the domain of special education. In the conclusion the gendered professionalism within special education schools is related to the status of expert knowledge and the involvement of an increasing number of women, in particular Catholic nuns, in schools for children with learning disabilities in the Netherlands in between the two world wars. (Contains 1 figure, 8 tables, and 70 footnotes.)