This study builds on the result from a survey sent to 120 early childhood teachers, four years after they completed a course in action research. The main findings indicated that many of the teachers had taken a leading role for their colleagues in the early childhood setting. The aim of this study is to understand the kinds of professional development and leading practices and the kind of relationships within and between them that are capable of transforming teacher and children´s practices. Seven early child hood settings were chosen for a deeper study. Teacher teams were interviewed while, at the same time, hey jointly constructed a mind-map that represents the teams’ collective understanding. These mind maps were key data for this study. The researcher and the teacher teams met four times during a six- month period, discussing, analysing and rewriting the mind-map. Three concepts ‘sayings’, doings’ and ‘relatings’ have been used in the analyses. It is evident, so far, that the teachers’ professional learning through the course in action research is realised in their work, which can be noted for example in how they relate to different aspects in action research when speaking about their work. It is also clear how the governing body, mentors and principals support action research. One such observation is that time is given for the teacher teams to discuss their work in regular compulsory staff meeting. From the mind-maps, it is also obvious that the teachers have impact on decisions taken for on-going professional development, based on their need for knowledge that they can act on in the interests of children’s learning. Our findings indicate that changing practice is not only a consequence of sending practitioners to a course for professional development; rather, it comes about by engaging practitioners in reconstructing their practice. The ways professional development and layers of leading hang together influence how teachers become engage in changing their practice.