This chapter speaks directly to the theoretical debate unfolding in the IR norms literature regarding contestation and its effects on norm evolution and norm cluster resiliency. While some scholars contend that contestatory challenges will result in norm decay, debates about norm applications and validity can also promote the legitimacy and resiliency of norm clusters. The analysis develops a model of a three-stage process by which contestation may foster resiliency within international norm clusters in the face of antipreneurial challenges: activation for accountability, dispersal, and adaptation. It then tests this model by comparing recent cases of challenges to the nuclear non-proliferation norm cluster and the ‘nuclear taboo’. Specifically, it examines and compares two high-profile cases of extreme forms of applicatory contestation—Trump administration nuclear threats and Russian threats to use tactical nuclear weapons in its war with Ukraine—along with systemic responses in the broader norm cluster. The chapter shows how norm clusters can become activated to demand accountability and to absorb, diffuse, and redirect the energy of contestatory challenges, boosting resiliency through flaw-tolerance. The chapter concludes with recommendations for further research into the multifaceted nature of the linkage between contestation and norm cluster resiliency.