The psychoanalyst Judith Kestenberg conducted extensive research on the children of Holocaust survivors and on child survivors. In her studies of the children of survivors, she sought to understand how traumatic experiences were transmitted from parents to their children and their psychological consequences. Her concept of “transposition”�, a psychological mechanism by which children are transposed into their parents' past and live in a double reality, stands out in this research. The analysis of this concept helps us to understand fundamental characteristics of mental development and the dynamics underlying family relationships. The aim of this article is to describe and systematise Kestenberg's theory of transposition through an analysis of this concept in several of her texts. First, the context of her work on the second generation of survivors is described. Next, the clinical case based on which she first described transposition is presented. The third part is an analysis of Kestenberg's conceptualisation of transposition throughout her work. In this last part, the various aspects of transposition are discussed: its relationship to the survival complex, identification and mourning; the concreteness of fantasies; the bodily expression of transposition; and the developmental context in which it occurs.