During the past fifteen years, the use of operational criteria for diagnosis in psychiatry assumed an ever increasing importance. The World Psychiatric Association felt consequently called upon to prepare an easily accessible review of diagnostic formulations and made the results of this work available for the occasion of the VII World Congress of Psychiatry held in 1983. The scope of the book published at that time in English and German, and subsequently followed up by Spanish (1986), Japanese (1986), and French (1987) editions was, however, restricted to schizophrenia and major affective disorders.

The success of the English version of those ‘Diagnostic criteria for schizophrenic and affective psychoses’ (Berner et al., 1983a) called for an effort to extend the content of the second edition to cover the entire group of ‘Functional Psychoses’. A greater number of authors was therefore employed on compilation of the second edition whose title reflects the added material. Whereas the first edition reviewed and evaluated a number of diagnostic criteria systems for schizophrenic and affective psychoses only, this new publication includes criteria pertaining also to schizoaffective and paranoid psychoses. We selected the criteria on the basis of their historical importance, their effect on currently applied diagnostic systems, their use in many parts of the world, and their scientific foundation. We crave the reader's understanding for the fact that, owing to limited space, we were obliged to concentrate on the systems prominently in use. Our commentaries, however, cover also a number of the lesser known ones.