The UN Observer Mission for Bougainville was established in 1998 as part of the Lincoln Agreement and mandated primarily to monitor the ceasefire. A small mission, it was often caught between government suspicion and the exaggerated expectations of the other side. The article outlines the different phases of the mission’s role, from the monitoring of the ceasefire to the facilitating of talks that lead to the Loloata Understanding and a compromise on Bougainville’s political status. The mission’s role was primarily to manage the talks and to individually pressure the sides towards a resolution. Subsequently the UN has undertaken a role in the control and disposal of weapons, although its political role in encouraging the parties’ commitment to peace continues.