This paper explores how to develop teacher leaders across the career span. It offers a conceptual framework with three central tenets of teacher leadership: an emphasis on inquiry, a social justice imperative and an expanded understanding of teachers' roles in schools, communities and society. This model foregrounds the primary role that teachers should play in building a more equitable, democratic society. The paper then presents a case study of how one institution is attempting to link the conceptual model with practical application. This includes revision of pre-service and graduate teacher education programmes as well as partnerships with local schools. The goals of applying this model in practice are threefold: building capacity for teacher leadership and ongoing inquiry throughout PreK-12 schools, preparing pre-service teachers to enter the profession with a broader understanding of their role and the capacities needed for creating change in schools, and building connections among different programmes and institutions in order to support sustainable change efforts. Throughout the paper we examine the complexities of working across time and space to support systemic change by centralising the development of teacher leaders.