We study the predictive power and associations of several psychopathology and temperament scales with respect to schizophrenia and other psychotic disorders. Measures of psychopathology (Physical and Social Anhedonia Scales, Perceptual Aberration Scale, Hypomanic Personality Scale, Bipolar II Scale, and Schizoidia Scale) and the Temperament and Character Inventory were included in the 31-year follow-up of the prospective Northern Finland 1966 birth cohort (N = 4926). The Perceptual Aberration Scale was the best scale for concurrent validity in psychoses, and also the best psychopathology scale in terms of discriminant validity. Participants scoring high in hypomanic personality were at the highest risk for developing psychosis during the 11-year follow-up. Harm avoidance was a dominant temperament dimension in individuals with psychosis compared with participants without psychiatric diagnoses. These scales are useful as vulnerability markers in studying psychoses.