In France, decentralization measures and the introduction of partial autonomy for secondary schools in the mid-1980s transformed the role of school principals. The legitimacy they enjoy today is the result of their new status obtained in 2001, which turned them into institutional leaders but also into the spokesperson of their schools. Since then, their training incorporates a larger managerial dimension, while maintaining their function as a relay in the hierarchical chain. To fulfil their new responsibilities and in response to the contrast in their basic training, the school principals created a specific culture based on different models of legitimacy distinct from the teaching education they received. Furthermore, an effective management of human resources requires the recognition of principals as educational leaders, which stands in contradiction with the pedagogical autonomy and professionalism demanded by teachers.