The writers consider that many diagnostic mistakes were made in war psychoses owing to the tendency to crowd cases into one of the two great pigeon-holes, manic-depressive insanity or dementia præcox, and that in many instances little attempt was made to understand the cases as reactions in terms of personality, conflicts and wishes. Many cases showing symptoms of these psychoses occurred in unadaptable individuals and the disorder readily cleared up upon removal to hospital. Many illustrative cases are given which enable the writers to conclude that: (1) affective disorders were frequently mistaken for dementia præcox; (2) psychoses showing typical schizophrenic development had recognisable benign features; (3) acute confusional hallucinatory psychoses with fear were incorrectly diagnosed as dementia præcox; (4) acute paranoia was a relatively common psychosis; (5) the distinction between psychosis and psychoneurosis is untenable.