Several clinical and experimental data suggest that some people with schizophrenia have an impaired ability to attribute relevant mental states to other people. We tested this notion in 24 schizophrenic patients and two control groups, who performed a task devised to test understanding of the intentions of nonverbal comic strip characters. Only the schizophrenic subjects with thought and speech disorganization had specific difficulties attributing mental states to others. The findings support cognitive models which postulate a link between planning process disorders and a deficit in mentalizing skills. The hypothesis that the more frequent an action is in everyday life, the more easily it is understood by schizophrenic subjects, is discussed.