Childhood trauma is a recognised risk factor for schizophrenia. It has been proposed that childhood trauma interferes with normal neurodevelopment, thereby establishing a biological vulnerability to schizophrenia. Poor premorbid adjustment is frequently a precursor to schizophrenia, and may be a manifestation of neurodevelopmental compromise. We investigated the relationship between childhood trauma and premorbid adjustment in 77 patients with first-episode schizophrenia spectrum disorders. We also investigated possible mediating roles for other selected risk factors in the relationship. We found several significant correlations between different trauma types and both social and academic premorbid adjustment from childhood to late adolescence. There were no significant moderating effects for family history of schizophrenia or family history of psychiatric disorder. History of obstetric complications, substance abuse and poor motor coordination weakened some of the associations between childhood trauma and premorbid adjustment, while poor sequencing of motor acts strengthened the association. Our results confirm previous studies indicating an association between childhood trauma and premorbid adjustment. Results indicate a general rather than specific association, apparent with different types of trauma, and affecting both social and academic components of premorbid adjustment across childhood, early and late adolescence. Further, our results suggest a complex interplay of various risk factors, supporting the notion of different pathways to psychosis.