Negotiation is a process that permeates our everyday lives. From international conflicts to corporate mergers, from labor contracts to distribution agreements, and from one-time job offers to the day-to-day of relationships, negotiation is one of the most common ways to reach agreement on disputed issues and resources. Though negotiation is challenging in the simplest of circumstances, a group context can make it even more complex: groups negotiating with other groups may argue among themselves; factions and coalitions may develop, leading to side deals or the obstruction of deals in...