In this article we attempt to explain how Spanish schoolteachers built their knowledge around Progressive Education and just how they assimilated these new teaching practices, a process we conceptualise as "appropriating the New". Our source consists of the 287 files presented by state schoolteachers from all of Spain as part of their candidacy in the competitive exams held in 1932 for the position of school headteacher. These files, which contain the professional history of each of these teachers, elaborated by him or herself, allow us to analyse the discourses and practices developed and used in their classrooms. Drawing on these teachers' accounts we have designed a typology with five different levels of appropriation of the ideas and practices of Progressive Education. These five categories are (1) Recognising the New; (2) Understanding the New; (3) Bonding with the New; (4) Applying the New; (5) Internalising the New. These levels, which represent the gradual implication of this sample of schoolteachers with the ideas of Progressive Education, bear witness to how their identification with these concepts led to a transformation of their teaching practices. We will then use this typology to study the appropriation of one of the best-known progressive ideas, i.e. self-government, which under the Second Republic of Spain in the 1930s acquired a particular political relevance.