From the very beginning in the field of organization development and action research there has been a central role afforded to the role conversation plays in enabling change to take place in social systems. Kurt Lewin himself actively pursued and developed settings in which conversation was the foundation for attitudinal and behavioral change. After his death, his colleagues and subsequently the scholars and practitioners who took his seminal research and insights into the world of organizations continued to explore ways in which conversation in groups could facilitate individual, group and organizational change. From T-group to team development, from the confrontation meeting to large group interventions, from intergroup conflict management to dialogue conferences, the heritage of Kurt Lewin has stamped itself on the applied behavioural science approach to change management that we know as organization development. In more recent years the work of Bohm, Isaacs, Schein and others has contributed significantly to the development of how conversation can be structured. The flourishing of large group interventions - open space technology, search conferences, future search, whole scale change - have created structures whereby whole systems can engage in simultaneous conversation about the future of their organizations and communities. Another distinctive characteristic of organization development is the role played by the external consultant. In organization development, consultants work in a facilitative, process consultation mode whereby they work at enabling members of the client system to perceive their own issues, understand them and develop and take their own actions in their regard.