Who gets a seat at the table and who does not is an important consideration for successful peacemaking. However, current research does not provide sufficient guidance for understanding the politics of participation in peace negotiations. This article develops a conceptual framework for understanding these dynamics. Its central theme is that the inclusion or exclusion of a given actor in peace negotiations is affected by two independent factors. One factor pertains to the practical requirements of the peace process and addresses the following question: does the participation of a given actor augment the chance of reaching a sustainable peace settlement? The other factor relates to the normative dimension of peace talks: is the participation of a given actor consistent with the values of international mediators and sponsors of peace negotiations? The article argues that the dynamics of inclusion and exclusion result from the interplay of these two factors. The most straightforward situation for mediators is when practical requirements and international norms are mutually reinforcing. Difficulties arise from scenarios where practical effectiveness and norms contradict each other. This is the case when the involvement of a given person (or group) is imperative in terms of the peace process, but difficult to justify politically because this person has committed terrorist acts or is indicted by an international court.