Aim. The aim of this article is to assess the influence of sociodemographic and clinical factors on social functioning in schizophrenic, affective and anxiety disorders. Method. Patients of age between 18 and 65, suffering from schizophrenia, affective or anxiety disorders and treated in mental hospitals in five European cities were examined at admission to hospital and 3 months after discharge. The Brief Psychiatric Rating Scale (BPRS) and Groningen Social Disability Schedule (GSDS) were used. Statistical methods (ANOVA and MANCOVA) were performed on the three groups investigated to assess the relation between social functioning and diagnosis. Results. Family situation, city of residence (in acute states) and BPRS mean scores were found to be significantly associated with the level of social disability among the group of patients with schizophrenia. In the group with affective disorders, the severity of the symptoms, city and occupational status (during remission) were associated with the level of social disability. In the group with anxiety disorders the severity of symptoms was correlated with the level of social disability. Age, study centre and hospitalization had a similar association, but only in acute states. Conclusions. The severity of psychopathological symptoms plays a significant role in determining the level of social functioning, regardless of the diagnosis. In all three diagnostic groups the city of residence determined the level of social disability, which was lowest in the two western cities (London, Dresden), and highest in Wroclaw. Being in a relationship is associated with a low level of social disability for patients with schizophrenia. Occupational activity is associated with a high level of social functioning for patients with affective disorders.