This text reviews the preventive diplomacy of the United Nations, suggesting that the Security Council is not well suited to the task. What is needed, it argues, is a less political and more professional approach, namely a larger (and more autonomous) role for the Secretary-General and the development of a greater specialist capacity within the Secretariat. The work gives appropriate weight to the importance of peace building, both before and after conflict, as an integral part of conflict prevention, and the United Nations' role therein.