This young woman is feeble-minded and should be classed as such. She is listed here with the border-line cases simply for the reason that she belongs to a group whose mental deficiency is almost never recognized without the aid of a psychological test. Probably no physician could be found who would diagnose the case, on the basis of a medical examination alone, as one of feeble-mindedness. _F. H. Boy, age 16-6; mental age 11-5; I Q approximately 72 (disregarding age above 16 years)._ Tested for three successive years without change of more than four points in I Q. Father a laborer, dull, subject to fits of rage, and beats the boy. Mother not far from border-line. F. H. has always had the best of school advantages and has been promoted to the seventh grade. Is really about equal to fifth-grade work. Fairly rapid and accurate in number combinations, but cannot solve arithmetical problems which require any reasoning. Reads with reasonable fluency, but with little understanding. Appears exceedingly good-natured, but was once suspended from school for hurling bricks at a fellow pupil. Played a "joke" on another pupil by fastening a dangerous, sharp-pointed, steel paper-file in the pupil's seat for him to sit down on. He is cruel, stubborn, and plays truant, but is fairly industrious when he gets a job as errand or delivery boy. Discharged once for taking money. F. H. is generally called "queer," but is not ordinarily thought of as feeble-minded. His deficiency is real, however, and it is altogether doubtful whether he will be able to make a living and to keep out of trouble, though he is now (at age 20) employed as messenger boy for the Western Union at $30 per month. This is considerably less than pick-and-shovel men get in the community where he lives. Delinquents and criminals often belong to this level of intelligence. _W. C. Boy, age 16-8; mental age 12; I Q 75 (disregarding age above 16 years)._ Father a college professor. All the other children in the family of unusually superior intelligence. When tested (four years ago) was trying to do seventh-grade work, but with little success. Wanted to leave school and learn farming, but father insisted on his getting the usual grammar-school and high-school education. Made $25 one summer by raising vegetables on a vacant lot. In the four years since the test was made he has managed to get into high school. Teachers say that in spite of his best efforts he learns next to nothing, and they regard him as hopelessly dull. Is docile, lacks all aggressiveness, looks stupid, and has head circumference an inch below normal.