In Greece the sector of Administration of Education is in the early stages of development. Furthermore, up until now there have been no systematic efforts to examine the ways of action and the everyday practice of managers within the school system. In this context, the contribution of this study is important because it provides a useful scientific knowledge concerning how the principals of schools manage and allocate their working time.The present dissertation focuses on the effective management of time by the principals of schools of primary and secondary education. The aims of the research are to investigate the importance of dimension of time in the performance of the principals, to refer the methods of time management and the time allocation of principals between different professional activities and to analyze the relationship that may exist between time management and the distribution of time in the different activities.