The study aimed to identify the degree of functional Performance assessment in the departments of Education in the Sultanate of Oman, through answering the following questions: 1. To what extent is the functional Performance assessment in the directorates education in the Sultanate of Oman is effective? 2. Are there significant differences at the level of significance (a=0.05) in the mean of the effectiveness of functional assessment in the directorates of education on Oman, due to their gender, years of experience and academic qualification? Society of the study contains all directorates of education in the Sultanate of Oman in academic year 2008-2009 of about (2226) administrative. The selected sample of the study was chosen randomly from the educational community, of about (556) person. A questionnaire of (50) points was distributed to achieve the goal of the study. It consists of five main areas: the assessment items of functional performance, the objectives of public reports and obstacles that prevent the assessment of functional performance. The main findings of the study after extracting semantics validity and reliability of instrument are: 1. The effectiveness of functional performance assessment in the directorates of education in the Sultanate of Oman was medium in all fields of study except for public functional Performance assessment reports was high. 2. There are significant differences in significance level (a=0.05) in the mean of functional performance assessment effectiveness in the directorates of education on Oman in the areas of study as a whole depending on the gender variable. 3. There are significant differences in significance level (a=0.05) in the mean of functional performance assessment effectiveness in the directorates of education in the Sultanate of Oman in the areas of study as a whole due to the years of experience variable and academic qualification variable. The study highlighted number of recommendations. The most important one is that the head administration set up guidance to show subordinates attributes of the elements used in the assessment process to compare their performance with their managers expectations. The heads managers of the functional performance assessment department should get enough workshop in this field. This is to up date their knowledge and learn modern methods and find the suitable ways to solve the problems that they might face during the assessment process. Also undertake a similar current study, but focus on the obstacles of functional performance assessment in the directorates of education in the Sultanate of Oman.