Abstract: This article examines the therapeutic relationship, a concept held by many to be fundamental to the identity of mental health nurses. While the therapeutic relationship was given formal expression in nursing theory in the middle of the last century, its origins can be traced to attendants' interpersonal practices in the asylum era. The dominance of medical understandings of mental distress, and the working-class status of asylum attendants, prevented the development of an account of mental health nursing based on attendants' relationships with asylum inmates. It was left to Peplau and other nursing theorists to describe mental health nursing as a therapeutic relationship in the 1940s and later. Some distinctive features of colonial life in New Zealand suggest that the ideal of the attendant as the embodiment of bourgeoisie values seems particularly unlikely to have been realised in the New Zealand context. However, New Zealand literature from the 20th century shows that the therapeutic relationship, as part of a general development of a therapeutic discourse, came to assume a central place in conceptualisations of mental health nursing. While the therapeutic relationship is not by itself a sufficient basis for professional continuity, it continues to play a fundamental role in mental health nurses' professional identity. The way in which the therapeutic relationship is articulated in the future will determine the meaning of the therapeutic relationship for future generations of mental health nurses.