A detailed case history of a fourteen-year-old girl with anorexia nervosa is used to illustrate Masterson's views of the etiology, clinical manifestations, psychodynamics, and treatment of patients with the borderline syndrome. His object-relations theory stresses the importance of developmental arrest in the separation-individuation stage, with a subsequent maintenance of splitting of both self- and object representations. Effort is continually made by the borderline to avoid abandonment depression, resulting in the inability to truly perceive the self as autonomous, differentiated, complete, and separate. Masterson demonstrates through the case history the ways in which his object-relations view amplifies and expands upon Hilde Bruch's interpersonal theory in the understanding of patients with anorexia nervosa.