1DC:05 captures new findings relevant to diagnosis in young children and addresses unresolved issues in the field since DC:03R was published in 2005. DC:05 is designed to help mental health and other professionals: recognize mental health and developmental challenges in infants and young children, through 5 years old; understand that relationships and psychosocial stressors contribute to mental health and developmental disorders and incorporate contextual factors into the diagnostic process; use diagnostic criteria effectively for classification, case formulation, and intervention; and facilitate research on mental health disorders in infants and young children.