Background: Few studies of the validity of the Global Assessment of Functioning (GAF) have been published and none has shown how GAF ratings are associated with concurrent ratings of symptoms and social functioning. This article provides such data.

Method: Patients suffering from schizophrenia were assessed at admission to hospital and at six- and 12-month follow-up, using the GAF, the Scale for the Assessment of Positive Symptoms (SAPS), the Scale for the Assessment of Negative Symptoms (SANS) and the Social Behaviour Schedule.

Results: GAF ratings were highly correlated with ratings of symptoms and social behaviour at both follow-ups but not at initial assessment, although the inter-rater reliabilities for the measures were good.

Conclusions: The GAF can be rated reliably after minimal training. It provides a valid summary of symptoms and social functioning among schizophrenic patients provided they are not assessed when suffering from acute psychotic episodes.