The Kinsey of the transsexual set has written a fascinating introduction to the problems of gender identity encountered in his research at the famous Johns Hopkins Gender Identity and Psychohormonal Research Unit clinics. It is here that those who have problems with ""gender schemas"" (appropriate sex-role behavior) or sexual identities (where body structures or genetic make-up are not in accord with a person's sense of being male or female) are studied, helped, and sometimes operated on: homosexuals, transvestites, hermaphrodites, and transsexuals. Both case histories and developmental data (pre and postnatal) are presented as the author gives fair hearing to both sides of the nature-nurture debate. Women Liberationists take heed -- the body, at every stage of uterine growth, tends toward the feminine: an undifferentiated gonad without the ""male"" chromosome will turn into an ovary; if the testicle fails to secrete a sufficient amount of androgen, the external genitalia (and later, the secondary characteristics) will be those of a female. This book performs a valuable service in making the Jan Morrises of the world comprehensible and sympathetic, and should open everybody's eyes to the complexities of this most basic determinant.