Cognitive deficits are vulnerability indicators for psychotic disorders, particularly schizophrenia. The deficits remain stable throughout the illness in schizophrenia, but fluctuate with clinical state in other psychotic disorders. They are limiting factors for patients' prognoses and there is considerable incentive to develop treatments that can improve these deficits. The current brief review summarizes the relevance of cognitive deficits for the pathogenesis and prognosis of psychotic disorders, and identifies pertinent issues within the research field.