This book addresses a central puzzle in ontological security theory, namely the relationship between identity continuity and change, and the role anxiety plays in fostering and inhibiting change. The work argues for a more nuanced perspective on how change and threats to national identity relate, thus advancing our understanding of the role anxiety plays in shaping state choices. The case studies of Sweden and Germany show that national identity can experience highly disruptive challenges when the external security environment changes. According to extant ontological security theory, these structural challenges should lead to heightened anxiety and identity crises as national narratives become unstable and fragile. Instead, empirical evidence shows that states turn ontological anxiety into strategies of anxiety abatement, management, and ontological innovation. The evidence also reveals that states go to extraordinary lengths to maintain existing narratives, discursively maneuvring between the twin needs of biographical continuity and responsiveness to change. In their efforts to adapt and preserve identity, states embrace ontological ambiguity; they neither fully respond to change, nor do they ignore it. Rather, they strive for discursive innovation where new interpretations of how to be are balanced with new interpretations of the meaning of necessary change. In the process, ontological ambiguity becomes the new normal. These findings suggest that Sweden and Germany may not be outliers, and that being and becoming is an inherent feature of social life all state actors must engage with. This book will be of interest to students of security studies, European politics, foreign policy, and international relations.