<p>Understanding the role of international norms has been a prominent theme in International Relations, alongside studying International Organizations (IOs) as norm diffusers. Combining both literatures, this article examines the conditions under which IOs create resilient policy norms. Resilience is defined as the ability of norms to retain their essential elements while being enacted over time. Drawing on informal governance, localization, and translation approaches in the IO and norms literature, we understand IOs as social sites where international norms are transformed into ‘policy norms’. We propound that norms emerging internally through bottom-up processes within IOs become more resilient owing to a better knowledge of the organizational culture and higher norm ownership by staff. We introduce four degrees of resilience—endurance, elasticity, flexibility, and fragility—which we illustrate empirically by comparing four policy cases: capital account liberalization and poverty reduction in the IMF, and anti-corruption and sustainable agriculture in the World Bank.</p>