The topic of this doctoral dissertation is Croatian vocational teachers' professional identity formation and development, while the main research question is: “How is professional identity formed and developed in Croatian vocational teachers?” Narrative inquiry was chosen in order to thoroughly examine the phenomenon of vocational teachers' professional identity both in the development of the interview protocol and field research, and in the analysis and presentation of the research results. Multiple steps were used in the analysis and data processing while the main approach was the three-dimensional spatial approach, i.e. the three-dimensional narrative analysis (Clandinin and Conelly, 2000). This analysis has yielded four types of narratives about the vocational teachers' professional identity, which point to several important conclusions. Namely, the results of the research emphasize the exceptional importance of personal biographies of vocational teachers that can contribute to or limit the processes of formation and development of their professional identity. The research results especially recognised the importance of previous educational and work experiences as well as personal values and attitudes which, in addition to having the function of self-reflection, guide the professional decisions of these teachers. The context of the institutions in which they are employed (schools) also seems to have a strong influence on the formation and development of the professional identity of vocational teachers, whereby the relationship with students with whom they are in direct and daily contact seems to be a crucial feature of their professional identity. In addition to the above, the results of the research indicate the commonality of unstructured mentoring of vocational teachers and the lack of support for balanced professional development in teaching and their first profession as well as in continuous and formal cooperation with the industry. Additionally, there is a noticeable discourse of very low status and reputation of secondary vocational schools, as well as the disinterest of educational policies and reforms for the needs of vocational teachers, which is in some cases reflected in their lack of motivation. Given the above findings, this doctoral dissertation offers recommendations at the level of vocational teachers, schools and the Ministry in order to address the necessary interventions at various levels in order to strengthen the professional identity of vocational teachers.