Reduced insight has been reported in a majority of patients with a psychotic disorder. Most studies have focused on associations with neurocognition, neglecting relations with social cognition. Two hundred seventy patients with nonaffective psychosis participated in this study, which was part of the GROUP (Genetic Risk and OUtcome of Psychosis)-project. Linear regression analyses were performed to investigate the predictive value of composite measures of neurocognition, social cognition, and clinical symptoms. The moderating effect of phase of illness was also investigated. Insight was measured with a composite measure, based on the insight item on the Positive And Negative Syndrome Scale (PANSS) and the Birchwood Insight Scale (BIS). Insight on the BIS and the PANSS correlated significantly (r = .406). All independent variables correlated with the insight composite measure. The additional effect of social cognition and clinical symptoms were both significant. Phase of illness was a moderating variable: In patients with recent-onset psychosis (ROP), none of the independent variables explained variance. In patients with multiple episode or chronic psychosis, both social cognition and clinical symptoms had additional effects and explained insight, along with neurocognition, together explaining 20% of the variance. These findings indicate that multiple factors are associated with insight in psychosis. Specifically, associations of insight with social cognitive and clinical symptom measures were observed, over and above a contribution of neurocognition. This supports theories that imply a role for deficient emotion recognition and mentalizing in reduced insight. Further studies need to investigate insight in ROP into more detail.