The United Nations Mission for the Referendum in Western Sahara (Arabic: بعثة الأمم المتحدة لتنظيم استفتاء في الصحراء الغربية; French: Mission des Nations Unies pour l'Organisation d'un Référendum au Sahara Occidental; Spanish: Misión de las Naciones Unidas para la Organización de un Referéndum en el Sáhara Occidental; MINURSO) is the United Nations peacekeeping mission in Western Sahara, established in 1991 under United Nations Security Council Resolution 690 as part of the Settlement Plan, which had paved way for a cease-fire in the conflict between Morocco and the Polisario Front (representing the Sahrawi Arab Democratic Republic) over the contested territory of Western Sahara (formerly Spanish Sahara).
MINURSO's mission was to monitor the cease-fire and to organize and conduct a referendum in accordance with the Settlement Plan, which would enable the Sahrawi people of Western Sahara to choose between integration with Morocco and independence. This was intended to constitute a Sahrawi exercise of self-determination, and thus complete Western Sahara's still-unfinished process of decolonization (Western Sahara is the last major territory remaining on the UN's list of non-decolonized territories.)