In trying to more broadly define outcome in the efficient long-term treatment of patients with schizophrenia it is necessary to consider not only a reduction in psychopathological symptoms but also a successful psychosocial reintegration. Thus, a more exact assessment of psychosocial functioning is needed. Since the GAF (Global Assessment of Functioning) scale and the SOFAS (Social and Occupational Functioning Assessment Scale) are less operationalized and confuse psychosocial facts with psychopathological symptoms, the Personal and Social Performance (PSP) scale was developed [Morosini, P.L., Magliano, L., Brambilla, L., Ugolini, S., Pioli, R. (2000). Development, reliability and acceptability of a new version of the DSM-IV Social and Occupational Functioning Assessment Scale (SOFAS) to assess routine social functioning. Acta Psychiatrica Scandinavica, 1001, 323-329.] containing the four main areas "socially useful activities, personal and social relationships, self-care, as well as disturbing and aggressive behaviour". Validation of the PSP scale was conducted in a sample of 62 patients with acute schizophrenia. Rating instruments were PSP, GAF, SOFAS, PANSS, CGI, and Mini-ICF-P (Mini-ICF-Rating for Mental Disorders). The results showed good reliability with alpha=.64-.84, high test-retest reliability as well as good inter-rater reliability for the PSP scale. Furthermore, PSP proved good validity with high correlations to GAF (r=.91), SOFAS (r=.91), and Mini-ICF-P (r=-.69). The hypothesis that more critically ill patients would show lower scores on PSP than lesser ill patients was only confirmed for PANSS negative symptoms. Thus, the findings prove the PSP scale to be a reliable and valid instrument for assessing social functioning of patients with schizophrenia during the course of treatment as well as in the acute state.