K's maternal grandparents are of Jewish origin, both born in America. The grandfather was a teacher, the grandmother was "in business." This grandmother was the seventh of twelve children. The youngest of these is said to be "a brilliant woman of executive ability." The eldest, at the age of 79, "reads all the papers, compares notes, etc." One of the brothers in this group was a physician, another a lawyer. A cousin of K teaches in Massachusetts Institute of Technology and was called during the First World War for special work in mathematics. This man's sister is an arch[a]eologist married to an archaeologist. Three of K's grandmother's sisters are teachers; another is an artist. No mentally deficient or totally incompetent persons are known among the ancestors. K has two siblings, brothers younger than himself. Both are reported to be "bright." _Father_. K's father is an electrician, a graduate of high school and of Cooper Union. He was born in Antigua and was 32 or 34 years old when K was born. One of his sisters is a high school teacher in Brooklyn; another is a nurse; another, a stenographer. _Mother_. K's mother is recorded as of American-Jewish origin. She was 30 or 31 years old when K was born. She is a graduate of high school and of Hunter College (A.B.), New York City, and holds a license to teach music in the New York City schools. At the date of records she was actively in service, teaching general subjects. She had taken three maternity leaves of absence. EARLY DEVELOPMENT K's parents rate him as a child with excellent health, sturdy but nervous. He may have had measles, but there were no other childhood illnesses except occasional colds. When tiny, he would wake up with "great imaginings." At a little older age he would cry "with high tension"; "he no longer does this." According to parents, K cut his first tooth at 6 months. He began to walk at about 20 months and to talk at about 2 years. He learned to read at about 3 years. "While still a baby in his carriage he could read 'ice' and he would read the billboards. Before 3 he would sit down with a book and read." At 5 years of age K wanted to discriminate in meaning between "bluff," "joke," and "fake." He is "untiring in his attention to books. He will sit with an American history, an English history, and Godey's _History of American Beginnings in Europe_ (which goes into Greece and Rome) and the dictionary around him, and will work at these for hours." At the age here reported K had no playmates. His younger brothers played by themselves. K did not like to play. His favorite recreations were reading and transferring pictures, and consulting almanacs and dictionaries. He has a passion for accuracy. He has as yet made no collections, and has no pets. He has no imaginary companions and no imaginary lands. MENTAL MEASUREMENTS