The growing literature on ontological security theory (OST) in international relations, ontological security studies (OSS), is characterized by great internal diversity. This internal pluralism is one of its greatest strengths, but it is also potentially confusing, for example, when different works using an ontological security lens arrive at contradictory conclusions without it being obvious why. In order to make sense of this diversity, this article traces two interrelated conceptual divergences related to the notion of anxiety. The first one concerns the observation that anxiety is seemingly both debilitating and an impediment to action, as well as a call to action, inspiring adaptation and change. The second divergence centers on whether ontological security is at all attainable, which is largely a matter of whether anxiety is best understood as an extraordinary and temporally limited condition or as an ever-present and normal part of life. This article argues that the divergent answers to these questions, and the problems they give rise to, are primarily the result of ambiguity with regard to the key concept of anxiety. The malleable nature of the concept of anxiety engenders deviating interpretations and applications among scholars. While awareness of these issues already goes a long way toward making sense of some of the diversity within OSS, this article further suggests ways to increase the conceptual clarity of anxiety and to address the two issues of change and attainability. Doing so increases our conceptual understanding of OST.