This article presents a Therapeutic Assessment (TA) case study of a woman recovering from 4 years of intense medical treatment for stage IV cancer. The inclusion and utility of using the Adult Attachment Projective Picture System (AAP) in the TA is highlighted. The client's attachment classification as unresolved helped identify that her current experiences with dissociation and problems restructuring her life following cancer remission were related to severe childhood sexual abuse, which she had suppressed for decades. The AAP also provided information regarding the unconscious defensive processes the client employed to cope with attachment distress and her inability to find comfort and support from others. These findings were instrumental in guiding the subsequent psychotherapy. The TA process, particularly the assessor-client relationship, facilitated an experience of containing her previously unintegrated and dysregulated affect. A single-case experiment using daily measurements suggested that participation in TA coincided with symptomatic improvements in multiple domains. These improvements were maintained during 4 months of biweekly psychotherapy after the completion of the TA. This case illustrates the applicability of the TA model in health care settings, demonstrates the usefulness of the AAP in the context of TA, and provides empirical support for the effectiveness of the TA model in initiating symptom improvement.