Co-authored by Louise Stoll, Carol Taylor, Karen Spence-Thomas and Chris Brown, An evidence-informed, collaborative professional learning resource for teacher leaders and other leaders working within and across schools is a collection of specially designed cards created to support and promote the professional learning and development of groups of teacher leaders. Catalyst is a professional learning tool intended to bring to life the findings of a collaborative research and development project carried out between researchers at the UCL Institute of Education and Challenge Partners, an informal national network of schools. The project investigated four The collection consists of two sets of resource cards and a clear and detailed facilitator guide – along with a bibliography and photocopiable resources for download – and has been designed for use by staff in schools in all contexts and across the entire student age range. Ultimately, the aim of the Catalyst process is Suitable for school leaders and educators looking to both expand and refine their conversations around change management, professional development and school improvement.