Borderline patients, by definition, tend to evoke intense and often unpleasant countertransference attitudes in the psychotherapist. The latter may respond with an attitude or behavior that is deleterious to the treatment. The author demonstrates the use of psychological testing to ascertain these pitfalls. One patient, for example, exhibited a stubbornly uncooperative stance in therapy. His test responses showed that he experienced the psychiatrist as a deceptive, intrusive, and dominant figure who, he feared, would rob him of his special secret. His negative, seemingly unproductive attitude was a way of protecting an amorphous, undifferentiated self. Armed with this information, the clinician could focus on the patients' adaptive use of secrets to maintain autonomy in the therapeutic situation. Two additional case illustrations are given.