Shared social identifications (family, community, nation, humanity) predict normative actions and psychological well-being and can be invoked discursively by leaders to mobilize their followers. We illustrate the potential for harnessing shared identities to mobilize resilient public responses against COVID-19. Study 1 explored which patterns of social identification predicted protective behaviors (personal hygiene, physical distancing), prosocial actions (helping proximal and distal others), and psychological well-being (mental well-being, depressive symptoms, anxiety) among 560 U.K. adults surveyed during lockdown. Study 2 contrasted Prime Minister Ardern's use of identity-based rhetoric to mobilize New Zealanders, with Prime Minister Johnson's use of individualistic appeals to the U.K. public. Our findings suggest how political leaders might beneficially use social identities in communications about extreme events.