The federal government should make preventing mental, emotional, and behavioral disorders and promoting mental health in young people a national priority, says a new report from the National Research Council and Institute of Medicine. These disorders -- which include depression, anxiety, conduct disorder, and substance abuse -- are about as common as fractured limbs in children and adolescents. Collectively, they take a tremendous toll on the well-being of young people and their families, costing the U.S. an estimated $247 billion annually, the report says.