The ABC-D of Boarding School Syndrome clarifies the anatomy of the series of psychological traumas and sexual abuses that contribute to what, in 2011, I first classified as Boarding School Syndrome. The premise is that going to boarding school at a young age may inflict emotional injuries with lasting psychological consequences. The purpose here, ten years on, is to elucidate more fully aspects of the trauma embedded in the earlier writings and in the book Boarding School Syndrome. Research over the intervening years has led to developing an understanding of this enduring harm as presented in adult psychotherapy patients. The initials ABC-D refer to the elements that constitute the multiple traumas suffered by the children: abandonment, bereavement, captivity and as a result, for some, disassociation. As a consequence, children may be vulnerable to sexual advances from paedophile adults, school bullies and the confusing, sexually charged, solace found in dormitories with other children. The accumulation of these events may have the long-term effect of distorting intimate relationships and adult sexuality.