Projective identification provides a clinical-level theory that may be of value to therapists in their efforts to organize and render meaningful the relationship between their own experience and the transference. It will be seen in the discussion of clinical material that from the perspective of projective identification many of the stalemates and dead-ends of therapy become data for the study of the transference and a medium through which the makeup of the patient's internal object world is communicated. The clinical and theoretical usefulness of the concept of projective identification has suffered from imprecision of definition. Psychotherapeutic work with hospitalized patients demands a mode of thought that integrates an understanding of the patient's intrapsychic state, the countertransference, and the nature of and context for the interpersonal interaction. The chapter also presents an overview of key concepts discussed in this book.