This chapter defines the notion of social roles and role relationships as well as interaction roles (speaker, addressee) at various levels (utterance, dialog, social relationship). Roles are part of a script or frame, which can be formalized as a dialog game. Roles are played by specific agents, but only if they qualify. Given a role, it is clear what the expertise, responsibilities, norms, and powers are of an agent who has adopted that role. We specifically analyze the roles of the explainer and explainee in an interactive everyday explanation dialog (explication).