Nurses caring for adolescent consumers with anorexia nervosa in the inpatient setting are challenged in a unique way, in that they are caring for people with whom they do not have a mutually held concept of well-being. Their efforts to ensure weight gain are frequently against the wishes of the consumer. This dissonance results in challenging interactions, where nursing care and authority may be undermined. This study investigated the dynamics of nurses’ authority within this context. Interviews with nurses (n = 10) were conducted and analysed through thematic analysis. Nurses reported that consumers, compelled by the psychopathology of anorexia nervosa, often sought to challenge or undermine their authority. Some nurses experienced the opposition and conflict as demoralizing, whereas others were able to maintain confidence in the therapeutic merit of their care. Younger, inexperienced nurses in this study were particularly vulnerable to interactions that mitigated their authority, due to their tendency to engage in friend-like relationships. Nurses caring for adolescents with anorexia nervosa should be prepared to be confronted by interactions that overtly and surreptitiously undermine their capacity to exercise professional authority. It is important that nurses recognize the importance of maintaining their authority, and how it can be threatened in subtle and unexpected ways.