Developmental Trauma Disorder (DTD) was proposed almost two decades ago as a psychiatric diagnosis for children and adolescents who were traumatically victimized and experienced severe disruption in primary attachment security. DTD was designed to complement post-traumatic stress disorder (PTSD) by identifying trauma-related biopsychosocial dysregulation not included in PTSD, many of which are attributed to other psychiatric disorders. In the past decade, evidence from clinician surveys and research field trial studies has provided evidence of DTD’s validity and status as often comorbid with but distinct from internalizing (including PTSD) and externalizing psychiatric disorders. Join Julian D. Ford, Ph.D., A.B.P.P., as he introduces the domains and symptoms of DTD that are assessed with a semi-structured interview developed and validated for the syndrome, observe examples of DTD symptoms in filmed therapy sessions, and be introduced to a meta-model with five essential principles to guide them in doing psychotherapy with DTD.