Children and teens who have conduct disorder behave in defiant and disruptive ways, such as violating social rules or hurting other people, for a period of 6 months or longer.

Younger children who have oppositional defiant disorder are sometimes later diagnosed with conduct disorder. Adults who have antisocial personality disorder often showed signs of a conduct disorder in childhood.

Children and teens with conduct disorder may:

• Harm or threaten to harm other people or animals, by bullying or threatening people, initiating physical fights, or being cruel to animals.
• Cause property damage or loss, by deliberately causing a fire or otherwise destroying property.
• Lie, cheat, or steal, by breaking into someone's house, shoplifting, and/or lying to obtain things that they want or to avoid consequences.
• Violate household or social rules, by staying out at night without permission from their parents, running away from home, or being absent from school without permission.

Treatment may include training for parents on how to handle the child or teen's behaviour, counselling for the child or teen, family counselling, and a special treatment plan in school. Some children and teens who have conduct disorder have other conditions such as attention deficit hyperactivity disorder (ADHD), depression, or anxiety, which also may need to be identified and treated.