This chapter aims to investigate the professional development of educational leadership based on the need to define and develop leadership in educational organisations that are in the middle of complex challenges and changing operational environments. The data of this study were collected through interviews and project descriptions of the key actors of the four key projects of the Ministry of Education and Culture, Finland. The data were analysed using problem-driven qualitative content analysis with inductive reasoning. The main results included both the common aspects, such as the development of education in educational leadership, and more project-specific aspects, such as an emphasis on the specific context, in these projects. Furthermore, it was found that the professional development of educational leadership could be supported when, for example, the need for flexibility and supportive networks are recognised. In addition, when describing the holistic development of the professional leadership in education, it is crucial to provide multi-form and equal development opportunities to individuals and communities at every level and in all leadership positions during their entire careers. The results of these development experiments can help both national and international audiences in the professional development of educational leadership in their educational systems.