The advances in science and technology over the last few centuries drive individuals to feel the need of constantly updating their knowledge and adding new ones for being useful in their society or continuing their personal development. Educational institutions, providing educational services, are under the influence of many factors while trying to reach the goals, set for them, and achieve the expected quality. One of the leading factors, that affect the quality of education in the school, is school principals, who are responsible for the administration of the school and lead the institution in identifying the vision and fulfilling its mission. The fact that principals, who have a common working environment with teachers, most basic element of education system, have the skills within the scope of educational leadership will contribute to the learning process of students and will also enable future generations to create value for the development of their countries. In this study, qualitative research method was used in order to determine the differences between the perspectives of principals, who had postgraduate education in the field of administration, and the contribution of the education, they received, to their professional and personal development. The differences between the perspectives of school principals, who had a master’s degree in educational administration, were assessed by their experiences and comments. In order to gain knowledge in the subjects, that are known but not completely analyzed, the case study pattern, one of the sub-units of qualitative research method, was used. Since the research area consist of predetermined group or criterion, the criterion sampling method was used. A semi-structured form with open-ended questions were created for ten school principals, who are working in Düzce and completed their postgraduate education. Furthermore, probe questions were created to help the participants understand each question better. After the interviews with the participating school principals, content of interviews was recorded as text files. These text files were analyzed and interpreted by using descriptive and content analysis approach. As a result of the analysis of the findings obtained, school principals, who had a master’s degree in the field of Education Management Supervision (EMS), stated that after the education they have received teachers trusted them, gave value, and accepted them. Their colleagues (other principals) advised them as an expert and approached them in positive manner however the senior managers of them approached them in negative manner (assessed the effect of education as worthless). School principals, who had a master’s degree in the field of EMS, stated that this education increased their professional competence, contributed to their personal development, developed a different perspective and strengthened their communication skills. When the research data was examined, it was seen that graduate education makes different contributions to the knowledge, skills, and attitude of school principals. Additionally, it was seen that school principals believe graduate education provides broad perspective to them. Furthermore, school principals stated that their communication skills, empathy skills and tendency to teamwork have been improved after graduate education. They also stated that these improvements have reflected positively on the corporate culture.