This text represents the first examination of both the theory and practice of co-therapy. It explores in depth the co-therapy relationship, its creation, and the potential therapeutic value of its successful utilization. The Practice of the Art of Co-Therapy considers why a therapist would choose to practice co-therapy, elucidating the major benefits for therapists and patients alike. The crucial points to be considered in choosing a co-therapist are thoroughly analyzed and, to facilitate the selection process, insightful questionnaires and other helpful tools are provided. The reasons underlying the success of co-therapy teams (e.g., compatibility, equality, communication) are highlighted, as are those factors leading to impasses and crises. Rounding out Part I is a demonstration of co-therapy in action as the authors chronicle their treatment of a borderline personality and a narcissistic personality using co-therapy. Part II features contributions from other master practitioners of co-therapy. Included among these is a model for viewing the co-therapy relationship as one that develops incrementally over time. Also offered are a highly personal account of a husband-wife co-therapy team in practice over two decades and a provocative commentary on co-therapy and the nature of the therapy process itself. Given that many therapists will practice co-therapy at some point in their careers, The Art of Co-Therapy satisfies a long-neglected need for a practical handbook geared to those just initiating a co-therapy relationship as well as those faced with the immediate challenge of working out a current co-therapy relationship.