The evolution of the complex school system from its origins to school autonomy explains why it has acquired the connotation of complexity over time. This synergy between organization and institution that has been developing has resulted in the identification of the leader and the manager in one and the same person, that is, the School Headmaster who acts as a function of continuous improvement. The characterizing aspects of the management function and the School Institution become: governance, leadership, manager, research, communication, organizational culture, and empowerment. Organizational culture, in this scenario, understood as the sharing of assumptions, meanings, values and behaviors, becomes the useful means of achieving the institutional mandate: the guarantee of every student's educational success.