The purpose of this study is to discover the actual role of the Educational supervisor in the teachers' professional development in the secondary school in the Sultanate of Oman as perceived by teachers of these schools. The study aims , as well, to identify the effect of a number of factors ( like gender, subject nature, educational region ). The sample of this study consists of ( 616 ) male and female teachers representing the secondary school teachers, in nine educational regions The study employs a questionnaire to identify the actual and expected role of the educational supervisor in the teachers' professional development after testing its reliability and validity. It is made of ( 66 ) items distributed over seven dimensions. To answer the questions of this study, means, standard deviations, T-test and ANOVA One-way followed by Scheffe test or Tukey test were employed wherever F- value was statistically significant. The results of this study indicate 1- That the degree of conducting educational supervision activities in the professional development of the secondary school teachers in the Sultanate of Oman, from the teachers' point of view, was below average at one dimension only. It is the dimension of the school environment and the local community. -There were statistically significant differences at the (æ = 0,01) level, in favour of females, in four supervision dimensions; the students, the instructional Media and Educational Technologies, Evaluation and measurement and the school environment and the local community. However, there were not any statistically significant differences at the (æ = 0,01) level in three supervision dimensions; developing the teachers' experiences, educational leadership and human relations and curriculum and teaching methods. With regard to the teachers' nationality, the results indicate that there were statistically significant differences at the (a = 0,05) level in all seven dimensions, and in favour of the Omanis. -Regarding the nature of the school subject, the results indicate that there were no statistically significant differences at the (R = 0,05) level in all seven dimensions except the dimension of measurement and evaluation, and all were in favour of the Maths. - With regard to the nature of the region of education, the results indicate that there were statistically significant differences at the 0.05 level in all seven dimensions except the dimension of students.