This practice-based study investigates the implications for NHS leadership, leadership development and organisation development of the current government's vision of the future NHS as set out in the NHS Improvement Plan (2004). The study is based on two projects; an in-depth organisation development programme located in a high security mental health hospital and a pilot project on the future role of leadership carried out on behalf of the five Strategic Health Authorities in London. The research paradigm is that of naturalistic inquiry using action research and a single case method involving participant observation. Focus groups and a modified Delphi-consultation are used to elicit views about future leadership roles and competences. The two-project design was developed to address the range of leadership roles to be explored, the interplay between leadership development and organisation development and the need to understand both current realities and future developments. The study concludes that successful realisation of the vision set out in the NHS Improvement Plan will require a re-conceptualisation of the roles and competences of both organisational leaders and leaders working at the interface with service users. The study suggests that organisational leaders will need to become adept at shaping the cultures and practices of organisations and systems of organisations (enabling leadership) whereas leaders working at the interface with service users will need to become adept at case management. The study also suggests that leadership development and organisation development need to be closely integrated if either is to make a worthwhile contribution to the development of the NHS. Finally, the study suggest that success in past or current leadership roles in the NHS is likely to be a poor predictor of future success as the leadership requirements of the future will be significantly different from those which prevail currently or which have prevailed in the recent past