The aim of this study is to investigate to what extent projects are used as as an assessment tool in Science subject for grades (7-9) in Governorate of Muscat schools. A descriptive approach was adopted. Stratified Random Sampling (SRS) was used to create a sample of (121) science teachers and (1356) students for grades 7 to 9 of Muscat Schools. The study was conducted in the second term of the academic year 2017/2018. To achieve that aims of the study, two questionnaires were used, one tailored for teachers and the other tailored for students. A form was designed to analyze some of the students' projects of grades (7-9). The items of this form were described by the researcher for accuracy assurance. The study tools were verified for validity by presenting them to a group of specialized examiners. The two questionnaires were verified for reliability by calculating the Internal Consistency (Cronbach's alpha) between the questionnaire items. Reliability of the teachers' questionnaire scored (0.92) and the students' questionnaire scored (0.75). To verify the reliability of the analysis form, Agreement percentage was calculated between the researcher analysis and an assistant teacher to (15) projects. Agreement percentage reached (86.67%). The study results show that "projects" as a continuous assessment tool, are used to medium extent from both Science teachers and students point of view. There is no significant difference in using projects attributed to the variable (Teachers' Gender) and the variable Teachers years of experience), while there is a significant difference in the difficulties facing the use of projects attributed to the variable (students gender) in favour of males. Variable (Class) is in favour of Class 7 in the implementation process of projects, and in favour of grade 8 & 9 in the difficulties facing the implementation. The results also show that students' science projects employ all aspects of the "project tool" stated in the student evaluation document for students in classes (5-10)" in general, Concluding from all above, the study recommends that it is significant to conduct sufficient training courses for science teachers, on how to design, conduct, and evaluate projects as a continuous assessment tool. It also recommends to establish a bank of ideas for projects for each class, in a way to give students the freedom to select from a wide range of choices according to their abilities and interests.