It is important that child and adolescent psychiatrists use their knowledge of infant developmental research to understand the origin of symptoms that present in later childhood, and that they use this knowledge in therapeutic planning. Although obtaining retrospective early life data may be difficult, strategies for working with families, parents and children, as well as medication selections for any DSM-5 diagnosed child, are appropriately influenced by such information. Attachment research provides ways of understanding how early developmental disruptions influence later behaviors, and may suggest more appropriate interventions with the child, caregiver, and family. Attendees learn to apply the principles of attachment research in their practice and to employ advances in developmental infant research to the psychotherapy of older children and adolescents.