Work with survivors of childhood trauma sheds light on the enigmatic subject of just how psychotherapy produces change. The focus of this paper is the observation that there are two fundamental change mechanisms in psychotherapy, catharsis and internalization. Each one has a different time course and different clinical characteristics including the role played by the therapeutic relationship. Catharsis is triggered by the presence of the empathically attuned therapist, while internalization is driven by the therapist's slightly aloof stance of expectancy and the patient's need for connection. Each mechanism has a different childhood origin. Taken together, these two mechanisms are sufficient to explain therapeutic gains in other forms of psychotherapy and with other pathologies.