This chapter traces the various stages of the complex relationship between Cambodia and the United Nations. It overviews the early days of Cambodia’s relationship with the UN through to the Khmer Rouge period, before considering the fractious relationship between the UN and the Phnom Penh government during the Vietnamese occupation. It then focuses on the UNTAC mission, which attempted to facilitate a transition from protracted civil war to a fledgling democracy. Since the 1993 election, UN agencies have dealt with the difficult task of monitoring human rights, ensuring protection of refugees, and negotiating the establishment of a UN-backed tribunal to investigate and prosecute mass crimes committed during the Khmer Rouge regime. The chapter concludes by considering what the future may hold for the Cambodia-UN relationship.