This study aimed to describe the causal beliefs of individuals experiencing psychosis, specifically exploring how they are developed and maintained. Individuals with experience of psychosis were recruited from mental health services for in-depth interviews. A thematic analysis was used to analyse transcripts and key themes were identified. Fifteen interviews were conducted. Individuals were engaged in the process of exploring explanations for their experiences and reported sophisticated models of causation. Participants described a change in their beliefs, with the cause of their experiences not immediately clear. Individuals generated their models via external (family, professionals) and internal (evaluative, positive affect) processes and reported differing levels of conviction in relation to their beliefs. Clinicians should take the opportunity to explore the causal beliefs of their service-users, as they are able to provide intelligent and thoughtful explanatory models. In particular, clinicians should be aware of the emotional impact of different aetiological models and their personal role in the development of a client's beliefs.