This book analyzes the achievements of the UN World Summit of September 2005 in the field of conflict prevention, human security, and the advancement of the security development nexus. The book examines the Summit Outcome Document, which contains important general endorsements of the objective to strengthen conflict prevention capacities at the UN and fully supports the mission of the Special Advisor of the Secretary General on the Prevention of Genocide. This document commits all Member States for the first time to develop a notion of "human security" that recognizes that all individuals, in particular vulnerable people, are entitled to freedom from fear and freedom from want. It embraces the concept of a "responsibility to protect" against genocide, ethnic cleansing, and crimes against humanity. The book looks at how the newly established Peacebuilding Commission can play an important overall preventive role, in particular by ensuring that post-conflict countries do not relapse into armed conflict. It suggests the upcoming Comprehensive Report on Conflict Prevention by the UN Secretary General and a new General Assembly Resolution should operationalize and implement the shift from reaction to prevention. The United Nations for the 21st Century supports the call for a special summit meeting in 2010 on conflict prevention and human security with the objective to adopt a Global Action Plan on Conflict Prevention and Human Security, which should specify concrete agreements for allocating the resources necessary to bring peace planning, conflict prevention, and peacebuilding strategies to fruition.