The U.S. Surgeon General has described children’s mental health as characterised by the achievement of expected social, emotional, and cognitive milestones; positive social relationships; and effective coping skills. These factors enable children to experience a positive quality of life across different social environments and be free from symptoms of mental illness. This entry examines factors contributing to children’s mental health, types of children’s mental health issues, research on children’s mental health, and mental health services targeting children and adolescents, including school-based interventions.