Evidence suggests that self-esteem is an important mechanism in pathways to psychosis. However, whether low or high self-esteem is associated with psychotic experiences remains unclear. Besides, a limited number of studies has investigated fluctuations in state self-esteem in psychotic patients. This study investigated cross-sectional and temporal associations of momentary self-esteem and fluctuations in self-esteem with psychotic symptoms in three groups with different levels of (familial) liability to psychotic disorder. Using the Experience Sampling Method (ESM), momentary self-esteem, fluctuations in self-esteem (i.e., variability and instability), and psychotic experiences, paranoia, negative symptoms (i.e., event anhedonia and social anhedonia), intensity of negative affect and altered affective experiences (instability and variability in negative affect) were assessed in 147 psychotic patients, 131 of their siblings and 113 controls. Lower levels of momentary self-esteem were associated with an increased intensity of psychotic experiences, paranoia and negative affect, with the magnitude of the associations