This chapter investigates the differing roles of teacher unions in Sweden and Finland. In Sweden, there are separate teacher unions for subject teachers, with their roots in the grammar-school tradition, and for class teachers, rooted in the folk-school tradition. In Finland, these two teacher categories were merged into one union in the early 1970s. The Swedish teacher unions have different views on the organisation and content of teacher education, with disagreements focused on lower secondary school, where both subject and class teachers claim the right to teach. This has been connected to ideological arguments, where subject teachers have defended the role of subject knowledge in teacher education, supported by the political centre-right, and class teachers have argued for the importance of general pedagogical skills, supported by the Social Democrats. This has led to new reforms of teacher education at every change of government since the 1970s. During this entire period, no new reforms of teacher education have taken place in Finland where the united teacher union has, in order to please both categories of teachers, emphasised flexibility and the importance of in-service training as a means of adapting teachers’ competencies for different student age groups.