Undoubtedly--and especially since the invention of psychological tests to determine the mental state of dullards--many children have been erroneously pronounced feeble-minded when their backwardness is in reality due to remediable causes. The trouble is not with the tests so much as with the inexperience of those who apply them, some of the tests being seemingly so easy of application that in many instances they have been utilised by teachers and others having little or no training in clinical psychology. This is particularly true concerning the application of the much-talked-about Binet-Simon method of mental diagnosis, devised by Doctor Alfred Binet and his colleague in scientific child study, Professor Simon. The Binet-Simon method is certainly simple enough, and, rightly used, is of great value. It was formulated by putting to hundreds of children, ranging in age from three to thirteen, a series of questions and commands of increasing difficulty, noting the results obtained, and selecting as "norms" for each age the questions and commands to which the majority of the children of that age were able to respond correctly. Thus it furnishes a convenient means for determining with considerable accuracy the degree of mental retardation of any particular child. Experience has shown, though, that its fixed standard, by which children are pronounced "mentally defective" if they fall three years behind the norm for their age, is not always an infallible guide. When the method is applied by the untrained investigator the result is sometimes absurd. For instance, in one American city 49.7 per cent. of six hundred retarded children tested by the Binet-Simon method were reported as being "feeble-minded," while 80 per cent. of three hundred children in the special classes of another city school system were similarly stigmatised. On such a basis we should have, among the six million retarded children in our schools, from three to nearly five million who are feeble-minded. Even if the Binet-Simon testing is done by an expert, there is always the danger of incorrect diagnosis, with resultant serious injustice to the child tested, unless the indications drawn from the testing are verified by careful clinical and laboratory investigation. A few cases from the experience of a well-known clinical psychologist, Doctor J. E. Wallace Wallin, director of the Psycho-Educational Clinic, Board of Education, St. Louis, may well be cited to illustrate and emphasise this important truth. There was once brought to Doctor Wallin a pupil in a private school, an attractive girl of seventeen, who was studying--or, rather, attempting to study--Latin, history, algebra, and English. Her teacher complained that she could remember little or nothing of what was taught her, that her attention flagged easily, and that in other ways she did not seem to be of normal mentality. And, in fact, tested by the Binet-Simon method she graded only eleven and a half years old.