genitalia. Most of Young's intersex patients were adults willingly seeking his help with physical problems of genital function. Demand for surgery increased dramatically with better understanding of the condition congenital adrenal hyperplasia (CAH) and availability of a new treatment (cortisone) by Lawson Wilkins, Frederick Bartter and others around 1950. For the first time, virilized infants with this variation were surviving and could be operated upon. A conflation was then established between life-saving treatment and cosmetic surgeries. Hormone assays and karyotyping to ascertain sex chromosomes, and the availability of testosterone for treatment led to partial understanding of androgen insensitivity syndrome. Within a decade, most intersex cases could be accurately diagnosed and their future development predicted with some degree of confidence. As the number of children with intersex conditions referred to Lawson Wilkins' new pediatric endocrinology clinic at Hopkins increased, it was recognized that doctors "couldn't tell by looking" at the external genitalia, and many errors of diagnosis based on outward appearance had led to anomalous sex assignments. Although it seems obvious now that a doctor could not announce to an eight-year-old boy and his parents that "we have just discovered that you are 'really' a girl, with female chromosomes, and ovaries and uterus inside, and we recommend that you change your sex to match your chromosomes and internal organs," a few such events occurred around the world as doctors and parents tried to make use of new information. Genital reconstructive surgery at that time was primarily performed on older children and adults. In the early 1950s, it consisted primarily of the ability to remove an unwanted or nonfunctional gonad, to bring a testis into a scrotum, to repair a milder chordee or to change the position of the urethra in hypospadias, to widen a vaginal opening, and to remove a clitoris. John Money, a pediatric clinical psychologist in the new "Psychohormonal Research Unit" at Hopkins, and his partners, John and Joan Hampson, analyzed these assignments and reassignments in an attempt to learn the timing and sources of gender identity. In most of these patients, gender identity seemed to follow the sex of assignment and sex of rearing more closely than it did genes or hormones. This apparent primacy of social learning over biology became part of the intellectual underpinning of the feminist movement of the 1960s. In its application to children with intersex conditions, this thesis that sex was a many-faceted