In this paper I put forward a hypothesis on a particular psycho-sexual determinant of anorexia nervosa in adolescent girls. I begin with an overview of existing literature which examines anorexia from psychiatric, demographic, medical, historical and psychoanalytic viewpoints. Drawing on the theories of Freud, Klein, Winnicott and Bion, and building on previous thinking, I posit a specific disturbance in the psychic development of the adolescent girl. I suggest that this amounts to her rebellion against the psychic onset of her future maternal capacities for reverie and containment. I link this disturbance to a pathological mother-daughter relationship and illustrate my hypothesis with a clinical account of intensive, long-term work with an adolescent girl. The high motivation and vivid dream material of this patient make for a particularly rewarding study.