Morrison et al. (Behav Cogn Psychother 23(3):265–280, 1995) have ­proposed a cognitive model which assumes that hallucinatory experiences arise from the externalisation of intrusive thoughts. According to this account, this externalising process is driven by the cognitive dissonance resulting from the experience of uncontrollable intrusive mental events and maladaptive metacognitive beliefs about the importance of thought consistency and the need to control thoughts. Over the past 15 years, a number of empirical studies have examined the presumed association between hallucinations and metacognitive beliefs in the attempt to test the empirical predictions of this cognitive model. This chapter provides an up-to-date critical review of the studies in this area. Despite some positive findings (mostly from non-clinical studies), the available evidence suggests that the association between metacognitive beliefs and hallucinations is not a particularly robust, and may be confounded by comorbid symptom dimensions that frequently covary with hallucination-proneness in clinical and non-clinical samples. Conversely, recent studies have indicated that metacognitive beliefs, although not directly implicated in the genesis of hallucinatory experiences, may represent an important determinant of hallucination-related distress, therefore representing a potential target for intervention. These results are discussed in relation to their potential clinical significance and future research into the role played by metacognitive beliefs in different symptoms of psychopathology.