This eight-country project is now in its fifth year and is an exacting, innovative collaboration which is investigating principals of schools in different countries and in different socio-economic contexts who achieve and sustain success. Using relatively common multi-perspective approaches and largely similar data collection techniques an unprecedented number (50) of elementary and secondary schools, the aim was to clarify the nature of successful principalship, how such leadership influences students’ learning and what lies behind (or gives rise to) it. The research aimed to uncover differences and similarities among countries in the ways success is defined and operationalised. This paper will provide an introduction to the contexts, purposes and processes; and a framework for sampling knowledge about principal leadership.

As previous literature has shown, the effects of successful principal leadership on pupil learning are largely indirect. In other words, the effects, in large part, are due to the extent to which principals may positively influence staff, students and the local community. This paper provides illustrations from the case studies of the application of the project’s analytical framework.  It identifies a substantial subset of important leadership (internal and external) antecedents, moderators and mediators which needed to be accounted for the future leadership research; and concludes that research on successful principalship must focus upon their leadership of organisations as both ‘machines’ and ‘living systems’.