DC:0-3 was the first developmentally based system for diagnosing mental health and developmental disorders in infants and toddlers. Its diagnostic categories reflected the consensus of a multidisciplinary group of experts in early childhood development and mental health. The newly revised DC:0-3R draws on empirical research and clinical practice that have occurred worldwide since 1994. DC:0-3R is designed to help mental health and other professionals. The features include: recognize mental health and developmental challenges in young children; understand how relationships and environmental factors contribute to mental health and developmental disorders; use diagnostic criteria effectively for classification and intervention; and work more effectively with parents and other professionals to develop effective treatment plans. DC:0-3R enhances your ability to prevent, diagnose, and treat mental health problems in the earliest years by identifying and describing disorders not addressed in other classification systems and by pointing the way to effective intervention approaches.