The UN celebrated its 70th anniversary in 2015. In the Volume Reforming the A Chronology by Joachim Muller an exciting story is told describing the evolution of the UN through the main change initiatives applied by each Secretary-General, characterized by political confrontations, crises of confidence and organizational constraints. Initiatives included approving the Sustainable Development Goals, strengthening peacekeeping, enlarging the Security Council, establishing mechanisms to protect human rights, improving aid efficiency, and reforming management practices. This story is completed by a Chronology of Reform Events to enhance the transparency of parallel, multi-layer reform tracks. Lessons learned highlight the main drivers of changes, the interests and constraints, and the dynamics of the reform valuable insight for capitalizing on future change opportunities.