The value of a rating scale for assessment in psychiatric disorders is that it facilitates the investigation of patterns of symptoms and their response to treatments. In a previous paper, Hamilton (1959), describing the construction and use of a rating scale designed for assessing the condition of patients suffering from depressive disorders, certain findings were described. In brief, it was found that much of the information given by the 17 variables of the rating scale could be given by four “index numbers” (dimensions, or factors). The nature of these factors was determined in two ways. In the first, the weights given to the symptoms which constituted the factors were examined. It was found (Table I) that the highest weights in the first factor were given to Depressed Mood, Guilt, Retardation, Loss of Insight, Suicide and Loss of Interest, in descending order. On this basis it was decided that the first factor corresponded to the classical clinical description of Retarded Depression. Examination of the weights given to the symptoms in the second, third and fourth factors, showed that these factors had no obvious correspondence with clinical syndromes.