Currently, there is not a robust, testable neural model available that sufficiently explains the development and maintenance of anorexia nervosa (AN) a severe, often fatal, adolescent-onset eating disorder. Using state of the art neuroimaging and neuropsychological techniques, our objective is to identify neural mechanisms in the adolescent brain underlying AN. This is of high clinical relevance in as much as it will provide a robust platform for a diagnostic battery so that physicians can identify those who are prone to develop AN at a very early stage of life. The aim of this research plan is: 1) To develop knowledge of cognitive dysfunction in adolescents who have recently been diagnosed with AN, with a battery of cognitive tests during a series of clinical visits. 2) To provide a scientific basis for our knowledge about how the brain of an adolescent with an eating disorder differs from that of a healthy adolescent, by conducting functional and structural magnetic resonance imaging on adolescent females with AN.