Childhood adversity and trauma are pervasive and have powerful, far-reaching consequences for health and well-being. Recent years have seen increased recognition of the need for trauma-informed practice, which aims to promote understanding, healing, and the prevention of retraumatization. Historical data show that the early Montessori schools were known internationally as healing schools, wherein children affected by adversity or trauma were apparently healed on a considerable scale. This study presents the findings from a documentary analysis of three primary sources, namely, Maria Montessori’s own original accounts, eyewitness accounts, and media reports pertaining to this healing aspect of the early Montessori schools. The findings demonstrate that, first, from the beginning of her career, Montessori worked with children who had experienced significant exposure to adversity or trauma, second, that her Montessori Method was shown to affect healing or recovery in these children, and third, that her long involvement with trauma-affected children directly led to her later attempts to set up an organization to be called the White Cross, which was to incorporate, among other things, a trauma-informed course for teacher–nurses. In this innovative approach to Montessori studies, we argue that Montessori was ahead of her time, that her work is even more relevant today in the context of adversity and trauma research, and that her methods, principles, and approaches may be harnessed and used in ways that promote trauma-informed practice in contemporary education settings.