Conduct Disorder is an extremely serious mental health diagnosis involving aggressive and cruel treatment of people and animals, destruction of property, theft, use of weapons, sexual abuse, serious violation of rules and other anti-social behaviors. It does not refer to mischief that normal children get into. I think your son's teacher did not mean to diagnose your son with a mental health condition; she probably just meant that he has been misbehaving. I think we should all be very cautious about using labels because they can certainly lead to unnecessary alarm and confusion.   Sarah Chana