Drawing on data from a Swedish participatory design-based study, this paper discusses the implementation of Active Learning Classrooms (ALC) in an upper-secondary school context. The main question in focus is: How did the teachers experience teaching in ALC in relation to the students’ ‘active learning’? Analysis of findings revealed four themes that are discussed in relation to a conceptual framework that brings together different aspects of educational practice, namely material, organisational, cultural and social aspects. The advantages of teaching in ALC were related to what was experienced by teachers as more focused collaborative work among the students and to the fact that activities and learning were based more on the students’ own thoughts and experiences than in the ordinary classroom. Challenges were related to composing groups where individual students could work well together and to keeping students working for long sessions.