Objectives: The main goal of the doctoral thesis was to investigate students' satisfaction with the quality of mentoring support in individual and group mentoring approaches, and to determine the contribution of the mentoring approach to the development of students' professional identity. Study design: Longitudinal, quasiexperimental, cohort research. Participants and methods: The study included 130 undergraduate nursing students. The survey instrument was a questionnaire. The first part of the questionnaire contained questions about the sociodemographic characteristics of the respondents, whereas the second part of the questionnaire consisted of two standardized validated questionnaires: the Professional Identity Five-Factor Scale (PIFFS) and the Mentoring Student Satisfaction Questionnaire (UVMP). Results: During clinical practice the individual mentoring approach was generally valued significantly more than the group approach by students in Group 1 (P = 0.012) and students in Group 2 (P = 0.022). A significant increase in student satisfaction with mentoring support was found among students from Group 1 in the individual mentoring approach following the group approach (P = 0.002). For students in Group 2, there was a significant decrease in satisfaction levels in the group mentoring approach that followed the individual approach (P = 0.011). Conducting clinical practice in the group mentoring approach had a significant effect on increasing the level of professional identity in the Knowledge dimension among students in Group 1 (P <0.001). There was a significant effect of the individual mentoring approach on increasing the level of professional identity in the dimension Perception of role models and professional future among students in Group 1 (P = 0.029) and students in Group 2 (P = 0.049). After completion of the two rounds of clinical practice, a significant contribution of the individual mentoring approach to student satisfaction with mentoring support was found (P = 0.021). No significant contribution of the mentoring approach to the level of professional identity was found in any of the three dimensions. Conclusion: Students were generally more satisfied with the quality of mentoring support in the individual mentoring approach. Conducting clinical practice in the group mentoring approach significantly contributed to increased levels of professional identity in the Knowledge dimension, and conducting clinical practice in the individual mentoring approach increased levels of PI in the Perception and Professional Future dimension.