As indicated in the symposium introduction, this paper outlines a theoretical framework to be employed in understanding practices of leading and of collaborative learning to be discussed in other papers in the symposium. This framework includes a theory of practice architectures that explains what practices are made of, and a theory of ecologies of practices that explains how practices relate to one another. According to the first theory, practices are composed of sayings, doings and relatings that hang together in distinctive projects, and they come to exist by drawing on discursive, material and social-political arrangements found in the places where the practices come to be enacted. According to the second theory, practices are connected with one another in ecological relationships involving interdependence among networks of practices. These theories allow us to understand practices – including practices like leading and collaborative learning – as living entities that have a life which is symbiotic with the lives of the people who enact them – people like students, teachers, school leaders and municipal educational administrators. This theoretical framework has been developed in a five year research program involving partner universities in Sweden, Norway, Finland, the Netherlands, the United Kingdom and Australia.