Anthropogenic climate change and the necessary transformation of society to mitigate its consequences constitutes an unprecedented educational challenge. Responding to the climate emergency and to society's awakening climate activism generates a complex situation for school leadership in particular. Here, we report findings from our research with climate activist students and teachers in Aotearoa New Zealand. We argue that school leadership plays a crucial role in enabling student and teacher agency and the development of effective Climate Change Education in schools. We utilise assemblage thinking, situating this within the new materialisms, to conceptualise schools and their leadership as dynamic assemblages, and we discuss teacher and student experiences as actors across such assemblages. We conclude that deterritorialisation and decoding of educational institutions and their leadership practices can promote and enable education to become a driver of the cultural transformation of society that the climate emergency mandates.