The paper brings together for the first time a sequence of six studies, from the one university faculty, on middle leaders from Australia, Chile and Singapore. All studies followed a consistent approach using multiple-perspective interviews. Middle leaders were seen to be key personnel in improving teaching and learning, and when they have well-defined roles and sufficient expectation and support were seen to be impacting on student outcomes. Yet too often they had limited impact, did not receive sufficient support from senior leaders, and worked in school structures that hindered their work.