Precocious puberty in girls has endocrinological as well as behavioral implications. We present data from a first systematic controlled follow-up study of 16 adolescent girls with a history of idiopathic precocious puberty (IPP) compared to closely pair-matched adolescent control subjects of comparable pubertal status and normal pubertal history. Findings in four areas of behavior are reported: Psychiatric sequelae: the IPP sample showed an increase in minor psychopathological symptoms. Psychosexual development: The IPP sample was advanced in sociosexual milestones, albeit mostly within the normal range for adolescents. Intelligence: IQ was not different from controls. However, school achievement was accelerated during childhood. Cognitive pattern: The IPP sample had lower spatial perception scores than controls.