This qualitative article discusses the nurse (known as the “reference nurse”) in charge of training, supervising, and evaluating student nurses undertaking in-service training in the care unit. The research describes the practice and position of the reference nurse (hereafter RN). The aim is to better understand the RN’s practice in training and supervising student nurses. Using an an approach which emphasizes mutual understanding, every RN is individually interviewed. The researchers then meet them again, this time in groups (by region), which enables discussions of certain positions which emerged from a first analysis of the interviews. Within a university hospital, twenty-four nurses working in internal medicine, psychiatry, and surgery were interviewed by a research team. The context of this research is distinctive in several respects. The research was carried out in partnership between two institutions—a university care institution and a nurse’s training institution. The research team includes people from both institutions. These two worlds have a shared function—to train nurses—but also have trends and themes specific to them, and which may even clash; all this comes in a context of educational and organizational changes to nursing training. The research themes are training and supervision activities, the evaluation of caring and educational practices, key moments of training and supervision, objective assessments of this role, and their ideals for it. RN described an informal system, essentially marked by key moments such as entering the care unit, welcoming the student, and exchanges with them, punctuated with educational and end-of-training assessments. RN developed forms of activities with the student which ensure the work will be carried out according to their responsibilities, while trying to adapt themselves, and interact with the student as well as with the contextual situation. The student’s questions are used as much to check their knowledge, their understanding of the caring situation, their ability to organize and to argue, as to understand their real-life experience and self-esteem better, to put them at ease, and to give them the confidence which will make their training easier. The quality of dialogic communication is strongly emphasized as necessary for training and supervision. Evaluation is an important part of supervisory work, and reference nurses actually showed a tension between a position of control and one of confidence in the practice of the student’s follow-up. RNs expressed a desire for specific time to train and supervise the student, would like to increase partnership with schools, and requested some educational support. Their discussions brought to light the various skills, technical as well as social, that this training and supervision role requires, but also the emancipatory impact of these various roles held.