Per cent. Considerably above ordinary in ability 3 Ordinary or fair in ability 55 Poor in ability 9 Mentally dull, but suffering from defective physical conditions, or disease, or bad habits, which may be the cause of the dullness 8 Sub-normal mentally, but not strictly feebleminded 8 Feebleminded (moron grade) 9 Feebleminded (imbecile grade) 1 Psychoses, ranging from well marked cases of insanity to temporary, but well-marked mental aberrations 7 I have found in various parts of the country considerable doubt expressed in regard to various statements which have been made of the proportions of the feebleminded which probably would be found by studying juvenile offenders. Teachers, judges, and probation officers have scouted the idea that there was upwards of 25 per cent. feebleminded among the children which come before a Juvenile court. Our own long investigation would certainly show otherwise. But of course we have never seen all of the thousands of children which come into the Chicago court yearly, so we have never been able to definitely answer the question of just what proportion is mentally defective. This year I have asked the assistant director of the Institute, Miss Bronner, to undertake at regular periods cross-section studies of the population temporarily held in the Detention Home. These probably would average lower than if one could see every case which was brought into court, for frequently the most normal children who have been engaged in a single offense are not brought into the Home. The results which she is obtaining I shall merely hint at, but they serve to show that the psychological study of delinquency involves very much more than the discrimination of the feebleminded. Any one who observed the considerable proportion of 7th and 8th grade and high school girls and boys who become severely delinquent will not be surprised at our findings. At least 91 per cent. of the girls and 84 per cent. of the boys have been found so far to group normal mentally, if we take the 12 year old tests of Binet as a standard. Now, as a matter of fact, I am not at all inclined without further investigation to denominate anyone as mentally defective who can not pass the 12 year test, because of the obvious weakness of these particular five tests for judging such an important point. But still we have been willing to place this criticism for the moment aside. There are several details of this given study which might be interesting to discuss, but this will be done elsewhere.