Professional development is a process that starts in education and continues through working life. To be a new graduated registered nurse has been described as difficult and tough. The healthcare organization, patients and nurses would all benefit if the professional development was smooth and supportive. The aim was to develop a model describing newly graduated registered nurses professional development during the first years of healthcare practice. To develop a model a constant comparative analysis was performed. Data consisted of written answers to an open question concerning what newly graduates perceived of particular significance to facilitate the transition between education and professional life. In this study the core concept constructed from data was mastering the professional role and was seen as a result of an ongoing process regarding the individual's experiences as well as relations with the surrounding environments. The analysis shows that the professional developmental process involves three interrelated sub-processes; Evaluating and re-evaluating educational experience, developing professional self-efficacy and developing clinical competence. These sub-processes are all influenced by six factors, social values and norms, the healthcare organization, nurse-management, coworkers, patients/relatives and private life situation. These factors affect nurse' professional development directly, indirectly or as mediating influences and can lead to various possible orientations. The result underlines the importance of knowing of how to develop the personal professional role within in a working life context inorder to experience to mastering the professional role. In this process the new registered nurses need support from both their nursing school and employer. This model will be the subject of further measurement and testing