Aim: Self‐esteem has been implicated in the development of psychotic phenomena, especially paranoia. Recent findings suggest that it may be useful to assess the instability of self‐esteem instead of the mean score. We examined this construct as two separate factors: positive beliefs about the self (PBS) and negative beliefs about the self (NBS). Theoretical models have implicated NBS in the development of paranoia, whereas research studies have sometimes found an association between PBS and negative symptoms. The first aim of this study was to investigate associations between change in PBS and NBS, and subsequent change in paranoia and negative symptoms. The second aim was to examine whether fluctuations in PBS and NBS predicted mean paranoia levels.

Methods: Data from a large sample of individuals with first‐episode psychosis (n = 256) assessed at baseline, 6 weeks, 3 months and 18 months was analysed.

Results: The data suggest that changes in both PBS and NBS in the early stages of disorder are related to change in negative symptoms, but not paranoia. PBS variability and NBS mean scores significantly predicted average paranoia levels when taken from across all four time points, suggesting potential differences in the associations with psychosis of these two constructs.

Conclusion: Self‐esteem boosting interventions administered in the first 6 weeks after admission to healthcare services may improve the subsequent course of negative symptoms.