In this chapter, the author describes the development of a transference psychosis with a view to formulating some hypotheses as to its nature. O. Kernberg states that a transference psychosis can readily arise in the therapy of borderline or psychotic patients and can be useful in facilitating our understanding of the genesis and psychopathology of their condition. H. Rosenfeld hypothesis is based on the finding that traumatized borderline patients are unable to accept interpretations about the destructive aspects of the self owing to the presence of a highly sadistic superego. With borderline or psychotic patients, it is, in the author’s view, of paramount importance to analyse the delusional psychopathological nuclei that lead to confusion between self and object or between parts of the self. The transference psychosis arises at the point when the image of the analyst coincides with the internal image of the pathological parent, thus rekindling the primal trauma.