Is sex identity a feature of one's mind or body, and is it a relational or intrinsic property? Who is in the best position to know a person's sex, do we each have a true sex, and is a person's sex an alterable characteristic? When a person's sex assignment changes, has the old self disappeared and a new one emerged, or, has only the public presentation of one's self changed? "You've Changed" examines the philosophical questions raised by the phenomenon of sex reassignment, and brings together the essays of scholars known for their work in gender, sexuality, queer, and disability studies, feminist epistemology and science studies, and philosophical accounts of personal identity. An interdisciplinary contribution to the emerging field of transgender studies, it will be of interest to students and scholars in a number of disciplines.