What is ontological (in)security? Recent scholarship on ontological security in International Relations has increasingly turned to the concept's theoretical origins in psychoanalysis and existential philosophy to address the field's (meta)theoretical limitations. This article argues that this development also necessitates an interrogation of the concept of ontological security itself to address the field's theoretical tensions. Further developing the nascent Kleinian approach to ontological security, this article conceptualises ontological (in)security as two distinct positions that denote the different ways in which subjects, be they individuals, groups, or states, manage anxiety. To develop this proposition, the article draws on Melanie Klein's work on the paranoid-schizoid and depressive positions to elucidate these positions of ontological (in)security, their respective defence mechanisms against anxiety, and their socio-political implications. This Kleinian approach facilitates a clear theoretical distinction between security and insecurity, providing an analytical toolbox to differentiate the various ways in which anxiety is managed in different positions. This framework particularly underscores the ethical, reparative, and transformative potential of the position of ontological security, aspects that have received limited theoretical and empirical attention to date.