The author outlines his clinical observations during the "middle game" of psychoanalysis, leading to recognition that structural change is taking place. "Middle game," "structure," process, and content are defined and critically discussed. Illustrative clinical vignettes are offered. The presentation emphasizes the importance of an active and resolving transference "struggle"; in addition, more traditionally noted criteria are briefly touched on, e.g., development of observing ego and treatment alliance, changes in dream function and communication, and the reviewing of the neurosis and transference during the termination phase as instances of mourning and working through. The concept of optimal psychobiological function in the service of a homeostatic principle is discussed.