The article discusses childhood mental disorders, focusing on their prevalence and associated factors. Anxiety disorders are the most common in children, followed by behavior, mood, and substance use disorders. Many children with one disorder also have a second one. Less than half of children with mental disorders get specialized treatment, but those with severe disorders are more likely to receive help. The field of child psychiatric epidemiology is working on improving classification and assessment methods, integrating child and adult psychiatric research, and studying both mental and medical disorders in children.