Researchers at CHOP are trying to improve outcome in the treatment of adolescents with anorexia nervosa. Eligible families will receive Family Based Treatment for anorexia nervosa. Some families will also receive Cognitive Remediation Therapy (a treatment that increases flexible thinking) for either the adolescent with anorexia nervosa or the adolescent's parents. Both parents are required to participate. Families will receive treatment for approximately 6 months, and will be asked to complete number of assessments during treatment and at two time points after treatment ends.