Problem statement: In the complex and changing educational context of the 21st century, the role of school principals has attracted the interest of many surveys as it is viewed as a key factor in school effectiveness. Purpose: The purposes of this study were (a) to investigate the role of school principals based on specific performance criteria, using as effectiveness indicators the perceptions of physical education (PE) teachers and their principals of effective school administration, (b) to determine whether statistically significant differences exist between PE teachers and principals regarding factors that express efficient school administration, and (c) to determine whether statistically significant differences exist in the perceptions of PE teachers and principals of the factor "work experience." Approach: A total of 415 teachers (223 PE teachers, 192 principals), who worked during the school year 2017-2018 in primary and secondary education in the prefectures of Pieria and Imathia of Greece, participated in the survey. The perceptions of PE teachers and school principals of efficient school administration were measured with a questionnaire created by Pashiardis and Orphanou (1999). Results: Results indicated that, in general, PE teachers were satisfied with their principal's management skills. Principals stated that they are more efficient than teachers think they are. A t-test revealed statistically significant differences in all the factors, in favor of principals. Α one-way analysis of variance revealed statistically significant differences in the factor "school programs" according to PE teachers with more than 20 years of work experience. Moreover, statistically significant differences were found in the factors "school climate," "problem-solving and decisionmaking," and "student management," in favor of older principals; in the factors "organization and administration" and "professional development of the principal," in favor of principals with 15-19 years of experience; and in the factor "cooperation with the ministry's officials," in favor of principals with 10-14 years of experience. Conclusions: There is a discrepancy between the perceptions of PE teachers and their principals of effective school administration. This suggests the need for improving principals' competence through specific training.