The authors present a fascinating case history of the successful resolution, in therapy, of separation-individuation problems in a bright identical twin woman in her early to mid-twenties. The case confirms the authors' hypothesis that twinning can interfere with the normal process of separation-individuation in the following pattern: 1) mothers may be forced to offer less than optimal need-fulfillment because of the added burdens of having two babies at once; 2) twins, frustrated by unmet needs, may turn to one another for solace, thus enhancing the development of symbiosis rather than separation; and 3) the private communications developed particularly by identical twins may alienate the mother and reinforce the symbiosis. This symbiosis may remain lifelong or may end in a delayed working through of separation-individuation in late adolescence or early adulthood.