Over the past two decades, International Relations scholars have highlighted the importance of efforts by hegemonic states and norm entrepreneurs to foster norm clarity when promoting the establishment, institutionalisation, and internalisation of norms. Yet, such analyses obscure the benefits of norm ambiguity in facilitating consensus, flexibility, and compliance. The authors offer a framework positing that hegemonic and institutional ambiguity can help create consensus and facilitate incremental reform necessary to sustain that consensus. Empirically, the authors then show how such ambiguity has facilitated the development of the responsibility to protect norm, tracing Rwanda-era debates over humanitarian intervention, Iraq-era backlash over interventionist abuses, and Libya-era norm implementation.