This article examines the role of state actors, organization agencies, and individual agents in diplomatic interactions and negotiations. States as diplomatic actors, organizations as diplomatic agencies, and individuals as diplomatic agents enter into complex and interdependent relationships. Proposing a three‐level analysis of interstate interactions and diplomatic negotiations, I argue that no diplomatic negotiation happens without interactions between parties at the state, organizational, and individual levels. The agency–structure paradigm provides a conceptual framework for understanding behavioral and structural properties of international interactions and their influence on diplomatic negotiations. Diplomatic negotiation employs specific forms of interaction, using a distinct language, protocol norms, symbols, ceremonies, and rituals. The state's “self” (as a social conception of its identity, values, and interests) affects the process of diplomatic negotiation. By managing, organizing, and improving international interactions at the actor, agency, and agent levels, negotiating parties can advance the process and effectiveness of diplomatic negotiation.