The National College for School Leadership (NCSL) was launched in 2000 with a remit to supervise and further enhance educational leadership development initiatives in England and Wales. Its corporate plan for 2003-07 set out a series of key objectives, which include a commitment to demonstrate the impact of the NCSL on school leadership. Some empirical evidence is beginning to emerge regarding the efficacy and impact of programmes delivered under the aegis of the NCSL but systematic studies of the ways in which school effectiveness is enhanced in schools that have been subject to multiple interventions in leadership development are less visible in the literature. This article reports on a study that included both a questionnaire survey and case studies of 10 schools which required school leaders, at all levels from middle managers to headteachers, to reflect on the impact that national programmes, both individually and cumulatively, were having on their personal professional development and on their schools as a whole. Findings of the study suggest that there is evidence that national leadership programmes are impacting positively on leadership in schools although the level of impact appears to be variable across programmes. The paper is offered as one contribution to the International Study of the Preparation of Principals (ISPP) project based at the University of Calgary.