Peace operations are increasingly multi-dimensional and are affecting ever more aspects of life at the grassroots level. While this evolution is necessary, it has created a tension in the field of legitimacy. Indeed, how can the United Nations possibly legitimise its actions in a domain traditionally subject to domestic laws and norms? International and domestic standards of legitimacy are clashing but neither of them is fully adapted to the particular case of peace operations. This article outlines a third approach to legitimacy centred on the UN Charter which incorporates the views of the entire legitimacy constituency of peace operations deployed in volatile environments.