In many European heritage early childhood education communities cultural-historical theory has become increasingly influential for informing practice. Yet one of the major challenges facing the field has been the slow mobilisation of new theory into practice. This paper reports on a study of 40 early childhood pre-service students as they moved from a developmental to a cultural-historical framework for observing and planning for young children. Although the study focused on pre-service teachers, the findings are demonstrably important for practising teachers.