The authors investigated for thinness and related eating pathology among high school girls in Japan in relation to their knowledge of eating disorders. In a Tokyo high school, the Eating Disorder Inventory-2 and the Child Depression Inventory were completed by girls aged 13-14, years (n = 243) and 15-16 years (n = 291), together with questionnaires on their knowledge of eating disorders. Japanese: teenagers are comparable to Western college students in the distribution of the drive for thinness scores. Senior high school girls show a stronger drive for thinness but this is not closely related to their BMI. Among junior high school girls, the degree of thinness is related to a higher BMI. Subjects who have had personal contact with eating disordered patients have the highest drive for thinness. Both age and knowledge are related to school children's attitudes to eating disorders. Copyright (C) 2004 John Wiley & Sons, Ltd and Eating Disorders Association.