WHAT IS KNOWN ABOUT THE SUBJECT?: The evaluation of nurse care practices poses many challenges, including the identification of all the aspects of the care given. Few studies have looked at the scope of nursing practice in psychiatry. However, the evaluation of care practices in the mental health field poses many challenges, including the identification of all aspects of care. WHAT THE DOCUMENT ADDS TO EXISTING KNOWLEDGE?: Findings demonstrated that mental health nurses do not invest in all domains of their scope of practice in the same way and the time spent with patients is low. Several factors contributed to this, including the increasing complexity of care, stagnant staffing levels, and a culture of care that continues to be influenced by the medical model. Current models of care still retain the stigma of this past, prioritizing medically delegated tasks rather than promoting a holistic approach to care. Although the professional identity of nurses is evolving and asserting itself, the paradigm shift in practice is still incomplete. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: It is essential to describe concretely what is actually expected of nurses, to help them allocate their time effectively and to identify opportunities for improvement. The field of practice of nurses is put under stress by a demanding work environment subject to many pressures and constraints. Changing practices so that nurses can use the full scope of nursing practice requires strong nursing leadership and action on education and the organization of care, particularly on clinical assessment. ABSTRACT: Introduction The evaluation of nursing care practices poses many challenges, including identifying all the aspects of the care given. However, few studies have examined the scope of nursing practice in psychiatry. Aim The aim of this study was to describe the intensity of nursing activities on a psychiatric unit based on the adaptation of Déry and D'Amour's (2017, Perspect Infirm Rev Off Ordre Infirm Qué, 14, 51) Scope of Nursing Practice Model. Method This 56-day descriptive observational study used the time and motion method to follow eight nurses. Results 500 h of observations were carried out. The greatest lengths of time were allocated to communication and coordination of care activities and to "non-healthcare" domains. Less time was devoted to activities related to clinical evaluation and therapeutic education. Discussion Findings demonstrated that MHNs do not perform all the possible functions in the domains of their scope of practice in the same way, and time spent with patients was short. Several factors contributed to this, including the fact that nurses are working in increasingly demanding care settings that keep them under constant pressure.