The 0-3 diagnostic classification of infant mental health, on the basis of DSM-IV-R, describes posttraumatic stress disorder (PTSD) as a pattern of symptoms that may be shown by children who have experienced a single traumatic event, a series of connected traumatic events, or chronic, enduring stress situations. This definition, related to young children, needs the consideration of several factors to understand the child's symptoms, organize the diagnostic process, and realize clinical interventions. In this sense, the clinician must appreciate the classification criteria of PTSD in early childhood in the context of the child's age, temperament, and developmental level. This report presents a review of the research in the domain of the PTSD in early childhood with particular attention to the developmental considerations to define critical diagnostic criteria, specifically organized on the child characteristics, competences, and needs. Along this line, it will describe two proposed modifications of the diagnostic classification in childhood: the Post Traumatic Stress Disorder Alternative Algorithm (PTSD-AA) and the definition of developmental trauma disorder (DTD).