The aim of this paper is to highlight the concept of professional identity of the nurse in order to promote theoretical clarity and examine implications for nursing practice. A modification of the hybrid model for concept development was followed. Accordingly, the theoretical analysis of conceptualizations and corresponding theoretical frameworks were combined with empirical data gathered from the field, from semi-structured interviews with eight registered nurses. The sampling was strategic and continuous. Personal and interpersonal dimensions and socio-historical aspects of the concept were found in the literature review as well as in the interview data. Attributes, antecedents and consequences of professional identity of the nurse in relation to the identified dimensions were stated. The analysis ends with a comprehensive description of the concept. Further, the relations to the concepts of self-esteem, self-image, professionalism and professional self-image, as well as professional function and roles of the nurse, are outlined. Finally, the importance of the developed concept is discussed, and suggestions for further research are presented.