This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part shows S. Freud’s discovery of the transference relationship that develops in the two-person relationship of psychotherapist and patient. In this relationship, impulses and phantasies from the past are transferred into the present relationship. The part suggests that the choice of partner is substantially determined by the drive to individuation, which “leads people to choose partners who will activate undeveloped aspects of their own selves”. It discusses the capacity of the couple relationship to function as a forum for psychological development. This is, of course, inherent in the intimacy and Intensity of a committed couple relationship. The concept of the unconscious contract in the couple relationship, therefore, offers a way of understanding the nature of partner choice and couple interaction and delineates the task for the couple psychotherapist when a couple present themselves for help.