This article examines the role of international humanitarian law (ihl) and humanitarian principles in the discourse of humanitarian negotiation. The article is based on extensive, semi-structured interviews conducted with 53 humanitarian practitioners about their experiences engaging in negotiations in the field. The article proceeds in four parts. Part 1 discusses two key factors at play during humanitarian negotiation processes. The first factor is the counterpart’s familiarity with relevant legal and normative frameworks. The second factor is the interests that can drive counterparts’ behavior. Part 2 presents a framework for understanding how the interaction of these two factors – familiarity and interest-alignment – can shape the discourse of humanitarian negotiation. Part 3 addresses the impact of these same issues on the humanitarian side of the negotiation. In particular, there is the possibility that humanitarian actors themselves might also lack familiarity with ihl and/or humanitarian principles and might find that their interests exist in tension with humanitarian laws and principles. The final section offers concluding remarks.