By referring to a therapeutic experience with a particular child, the following points are brought out: (1) The diagnosis of 'borderline' is often overlooked and confused with a mixed neurotic picture. The history of a prolonged relationship with a transitional object should make one think of this diagnosis. (2) In the borderline patient, the transitional object does not disappear, but merely becomes disguised in the form of a shifting transitional object. (3) The selection of the persisting transitional object is random, the specific object chosen not being as important as the properties with which the patient's imagination endows it. (4) The possible use in the therapeutic process of the transitional object and its variations is considered.