At a time when gender diversity is gaining increasing public attention, this book presents a poignant account of the current policy approaches to self-determining sex and gender in the UK and beyond. Davy shows how legal, medical and pedagogical policy developments are interconnected, while unique interviews with parents of sex/gender expansive children reveal how policy affects and is affected by experiences and advocacy. Written by an internationally renowned scholar, this book sparks new debate on the challenges and opportunities surrounding sex/gender self-determination.