Reform is a structural state of the UN and of its adaptation to its environment. Since their inception, the United Nations are engaged in a constant reform, which stages are shaped by crises. This is particularly true in peacekeeping where the operations are an instrument that the framers of the UN Charter had not considered, but that are the UN’s most important and well-known activity today. The Brahimi Report structured the ongoing peacekeeping reform process since 2000, and became a major reference for the reports that ensued, including the last one (« New Horizon »). Thus, peacekeeping was professionalized and rules and procedures were established for operations’ conduct. However, has this decade-long reform process led to a common vision of Member States on the limits and challenges of UN peacekeeping ? Will all these efforts avoid the UN to go back to its bad habits and made it able to face the political constraints ?