This study aims at identifying the extent of Oman Post-Basic education principals exercising their supervisory role in the light of Outcome-Based Supervision (OBS) from teachers' point of view, and at determining whether there are differences of statistical significance among samples in view of gender, experience and academic qualification variables. In order to achieve the study objectives, the researcher has adopted the descriptive approach, prepared a (45) items questionnaire under three themes: planning of outcomes phase, implementationof the outcomes and follow-up phase, and evaluation outcomes phase. After extracting the semantics of validity and reliability of the instrument, the tool have been applied to a random sample of (560) teachers. After processing the data statistically using the statistical package (SPSS) study found the following results: 1- The extent of Oman post-basic education schools directors exercising their supervisory role in the light of OBS was moderate. 2- Differences of statistical significance due to gender variable were in favour of females, and those due to academic qualification were in favour of post-graduates. 3- Absence of significant statistical differences were due to variable experience. The study found a set of proposed actions and suggestions that may contribute to activating the practice of post- basic education in the Sultanate of Oman of school principals Exercising for their supervisory role in the Light of Outcome-Based Supervision.