This essay contends that Oslo, as a back-channel negotiation, grew out of and was implemented within a complex communication system. This system consists of six elements: the roles of multiple agents, the patterns of interaction among the agents, communication across the sides, overlapping inputs from negotiation channels, the roles of mediators, and the use of communication modes. Back-channel negotiations are characterized by concerns for legitimacy, secrecy, keeping the talks moving, and leveraging both sides to remain at the table. The Oslo system evolved through the use of multiple agents to enhance legitimacy and the use of chain patterns to filter information and persuade principals. The Norwegian mediators acted as facilitators to build relationships between the sides, leverage costs and benefits of working together, and accelerate the speed of the talks through using multiple modes of communication. Overall, the communication system preserved the secrecy of the process through special codes for telephone conversations and through traveling to multiple sites outside of Oslo for meetings. Ironically, the secrecy and expediency of the process also created an insular system, one in which the principals experienced selective bias and illusions of unanimity.