It is widely recognised that the leadership of school principals is a crucial factor in school-based curriculum change. With the recent introduction of a new national curriculum in New Zealand, schools will need to develop strategies to incorporate this new curriculum into their programmes. This paper outlines evidence from international literature about how the leadership of principals is linked to change. It also examines evidence from case studies of early adopter schools. A major finding is that there appear to be common factors at work across effective secondary school principals, in particular an enthusiasm for proactive leadership of changes in school culture involving fundamental shifts in thinking and behaviour.