Background: Developing a therapeutic relationship with consumers is considered as the central aspect of nursing work in mental health. The importance of this relationship stems from its association with enhanced patient care and improved patient outcomes. Factors within the practice environment may influence the nurse's ability to engage effectively in this relationship. Objective: This study explored a model that added characteristics of the individual and practice environment to a central framework incorporating therapeutic commitment: a nurse's ability and willingness to engage in a therapeutic relationship. Setting and participants: Data were collected at six mental health nursing units in five public general acute hospitals in New South Wales, Australia for 14 days per unit, between 2005 and 2006. All nurses in participating wards were invited to partake in the study. Seventy-six (51%) responses were analyzed. Method: The data were collected using a Nurse Survey inclusive of the Practice Environment Scale of the Nursing Work Index (NWI-PES), and the Mental Health Problems Perception Questionnaire (MHPPQ). A Unit Profile form was used concurrently to collect staffing, skill mix and patient turnover data. Partial least squares path modeling (PLS-PM) was chosen as the analytical method to test the model and identify the most influential factors. Results: Experienced nurses who perceived themselves to be competent and supported were more likely to express a willingness to engage therapeutically with patients. Environmental factors associated with these perceptions included foundations of quality nursing care, opportunities to participate in hospital affairs and clinical supervision. Not all elements in the proposed model were supported. Conclusion: Positive hospital practice environments can improve the capacity of nurses working in mental health to engage therapeutically with patients. Specific approaches may include access to preceptorship, continued education and career development opportunities, together with clinical supervision, improved continuity of care, and the involvement of mental health nurses in the governance of the hospital.