This article reports about a study of nurses' limit-setting in mental health and the rationality behind correcting and therapeutic limit-setting interventions. Based on action science design, the study comprised three phases; namely a descriptive, reflective and concluding phase. Qualitative data were collected from various data sources; namely participant observations, interviews and written narratives. Eleven nurses participated. The main findings relate nurses' limit-setting interventions to two simultaneous and conflicting perspectives. That is: the dominating perspective of correcting, aimed at changing patients' behaviour by external control through three nursing roles of caregiver, educator and gatekeeper; the weaker perspective of acknowledging, where patients are seen as capable of changing themselves from within. The nurse's role reflects compassion and values patients' integrity. The nurses' work was based on a rationality of coping, because of a balancing act between the two perspectives and conflicting intrapersonal feelings aroused in challenging encounters with patients and colleagues. In reflection groups, relational interventions were developed, grounded in wondering reflection. Patients were regarded as participants in an open dialogue with the aim of securing collaboration.