Introduction The Schizophrenia Cognition Rating Scale (SCoRS), an interview-based assessment of cognition, has proved to be a valid measure of cognitive performance in patients with schizophrenia. Objective The aims of this study were to analyze the validity of this scale in a naturalistic setting representative of the Italian system of psychiatric care, and to test whether the SCoRS could be appropriately used in different phases of illness and contexts of care. Methods Eighty-six patients with schizophrenia (DSM-IV-TR criteria) (N=59 clinically stabilized patients; N=27 recently hospitalized patients) were administered the SCoRS. The reliability of SCoRS was assessed and global ratings were correlated with neurocognitive, clinical, and psychosocial functioning measures. Results SCoRS inter-rater and test–retest reliability were high. In clinically stabilized patients, SCoRS global ratings were significantly correlated with composite scores of cognitive performance (global cognitive index: r=−0.570, P<0.001), symptoms (Positive and Negative Syndrome Scale (PANSS) total score: r=0.602, P<0.001), and psychosocial functioning (Global Assessment of Functioning (GAF): r=−0.532, P<0.001; Health of the Nation Outcome Scale (HoNOS): r=0.433, P<0.001). On the other hand, no such correlations were found in recently hospitalized patients. Correlations with neuropsychological and functional measures were less significant as the severity of the patients' symptoms, especially positive symptoms, increased. Conclusion The SCoRS is a valid measure of cognitive performance and is related to psychosocial functioning, especially in clinically stable patients with schizophrenia. The usefulness of the SCoRS in patients recently admitted to hospital for an acute phase of illness is uncertain.