Despite the fact that there is increasing integration of Buddhist principles and practices into Western mental health and applied psychological disciplines, there appears to be limited understanding in Western psychology of the assumptions that underlie a Buddhist model of mental illness. The concept of ontological addiction was introduced and formulated in order to narrow some of the disconnect between Buddhist and Western models of mental illness and to foster effective assimilation of Buddhist practices and principles into mental health research and practice. Ontological addiction refers to the maladaptive condition whereby an individual is addicted to the belief that they inherently exist. The purposes of the present paper are to (i) classify ontological addiction in terms of its definition, symptoms, prevalence, and functional consequences, (ii) examine the etiology of the condition, and (iii) appraise both the traditional Buddhist and contemporary empirical literature in order to outline effective treatment strategies. An assessment of the extent to which ontological addiction meets the clinical criteria for addiction suggests that ontological addiction is a chronic and valid—albeit functionally distinct (i.e., when compared to chemical and behavioral addictions)—form of addiction. However, despite the protracted and pervasive nature of the condition, recent empirical findings add support to ancient Buddhist teachings and suggest that addiction to selfhood can be overcome by a treatment process involving phases of (i) becoming aware of the imputed self, (ii) deconstructing the imputed self, and (iii) reconstructing a dynamic and non-dual self.