Legitimacy has become a widespread term within policy documents of international organizations, not least international peacekeeping. But legitimacy is also a contested concept, so it matters greatly how it is understood on the ground. In this article, I ask what meanings the UN Department of Peace Operations attributes to the concept of legitimacy. Using a qualitative content analysis to study policy and training documents published by the department, I argue that the department understands the local legitimacy of UN peacekeeping missions as a (mis-)perception of its international legitimacy and underappreciates how other actors might undermine UN and state legitimacy.