WHAT IS KNOWN ON THE SUBJECT?: It is generally accepted that all interventions carried out by mental health nurses involve engagement with the patient; this engagement is a process that is gradually constructed and is not immediate. In Spain during last decade, nurses working in assertive outreach teams have gradually replaced the traditional institutional setting in favour of environments that are more familiar to the patient. In contrast, when patients and nurses interact outside institutional settings, a new approach and skillset is required in order to adapt to the new environment. WHAT THE PAPER ADDS TO EXISTING KNOWLEDGE?: We have systematically identified and assessed the available evidence on how nurses work in assertive outreach team programmes. The therapeutic link is not just assistance; it is actually a construct, which is established between nurse and patient, with the aim of favouring, fostering and strengthening the therapeutic relationship. Only a few studies have discussed the nurse-patient therapeutic link in assertive outreach services. However, it seems important that nurses use a standardized language, that is, a language promoted as a model of correct use and used for functions of greater prestige, especially in public administration and teaching, to integrate it into the theoretical framework. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: With the synthesis that we present, we hope that it promote a more consistent use of the engagement concept in research on this topic. In turn, this will enhance staff support and training and will foster evidence-based practice. The conceptualization of nursing language and its use by professionals helps to improve practice and the lack of a theoretical framework with a nurse perspective. It is necessary to establish a consensus between mental health nurses around the engagement' meaning in the programmes of assertive outreach teams. ABSTRACT: Introduction During last decade in Spain, nurses working in assertive outreach programmes have replaced the traditional institutional setting in favour of the patient's own environment. Engagement with patients requires a different skillset when the axis of the nurse-patient interaction is the patient's own environment. The engagement alone could be associated with the innate concept of patient's care and the helping relationship. However, in the individualized care models, the engagement seems to be an instrument with its own characteristics for the purpose of providing mental health care. Aim/Question To systematically identify and assess the empirical evidence on the relationships and engagement between patients with mental illness (schizophrenia, psychotic disorders, schizoaffective disorders, mood disorders and disorders of adult personality) and nursing mental health nurses. Method Systematic literature review based on PRISMA guidance. Results We identified and reviewed seven primary research studies. Following the analytic processes, three themes emerged: existence of different engagement levels, training needs and skills in the creation and consolidation of the engagement, and engagement as process. Discussion The engagement of nurse and patient is understood as a process that incorporates different stages. Whilst it is established, the engagement is subject to positive and negative influences. For the creation of the engagement and its maintenance specialized skills, knowledge and personal attributes (resilience, psychosocial skills, compressive knowledge of mental health illnesses, capacity to build effective relationships, adaptability and problem-solving) are necessary, but the main focus is on context where it develops, selected by the patient himself, for example, his home. Implications for Practice Administrators may have questions about appropriate hiring practices for assertive outreach teams since certain skills are necessary to obtain un engagement process, and staff training should be considered a key issue to provide specific skills for enhancing engagement and the therapeutic relationship. Conclusion The engagement must be understood as a long-term process. For the creation of the engagement and its maintenance, specialized skills, knowledge and personal attributes are necessary.