Objective: The authors demonstrate that the teaching of professional boundaries in psychiatry is an essential component of training to prevent harm to patients and to the profession. Methods: The authors illustrate overarching principles that apply to didactic teaching in seminars and to psychotherapy supervision. Results: The teaching of boundaries must be based in sound clinical theory and technique so that transference, countertransference, and frame theory are seen as interwoven with the concept of boundaries and must use case-based learning so that a "one-size-fits-all" approach is avoided. Conclusion: The emphasis in teaching should be on both the clinician's temptations and the management of the patient's wish to transgress therapeutic boundaries.