There is growing clinical evidence implicating disturbances in the separation-individuation phase of child development to adult psychopathology, particularly the borderline personality disorder. The clinical manifestations of such disturbance have been described by several clinicians and theoreticians. The authors have developed an inventory, based on these observations, designed to assess adult manifestations of disturbances in the separation-individuation process. The inventory was given to subjects meeting DSM-III criteria for borderline personality disorders and to a random university employee control group. The subject group had significantly higher scores than the control group. Although more research is needed to further establish the inventory's validity and reliabilty and to better define its scoring, the preliminary data indicate that it does assess adult manifestations of pathology in this developmental process.