The main purpose of this research was to investigate the verbal characteristics of the philologists as school leaders in secondary educational institutions and to evaluate their effectiveness in verbal communication with teachers. The investigation of the verbal behaviour of philologist principals is considered particularly important as, according to a recent demographic study, scholars rank first in the number of serving principals in secondary educational institutions in Greece. A qualitative methodology with semi-structured interviews and a combination of mixed purposeful sampling strategies were used to achieve the research goal. A total of 45 participants were selected from educational institutions of Athens Secondary Education: 15 principals who are philologists, 15 vice-principals and 15 teachers who are mathematicians. Parallel to that, the strategy of data triangulation from three perspectives: the philologist leader's, the vice-principal's and one mathematician's from the same school institution has been applied. A key factor in effective verbal communication was the principal's personality with their ethical-spiritual characteristics, not their scientific expertise. This research seeks to identify the most efficient way of communication between teachers and principals for the optimisation of the school's means and processes, taking into consideration the difficulties deriving from the teachers' different scientific backgrounds.