The study aimed to know "the effectiveness of the differentiated instruction strategy in the achievement of eighth grade students in the Sultanate of Oman, specifically in Islamic education and their attitudes towards it". To achieve the objectives of the study, the researcher depended on the quasi-experimental design. Two study tools were designed. An achievement test consists of (13) questions, and the measure of student trends towards Islamic education that consists of four dimensions with (27) paragraphs: (Student trend towards the benefit of studying Islamic education, student trend towards success in Islamic education, student trend towards confidence in the learning of Islamic education, and student trend towards the teacher of Islamic education). Also, a teacher's guide has been prepared to illustrate how to apply the differentiated instruction in teaching "moderation in Islam" unit from the eighth basic grade second semester. The study has been applied to a sample of (47) students from the eighth basic grade in southern Batinah Governorate, who were chosen intentionally. After collecting the data, the researcher analyzed the data using the statistical packages of social sciences (SPSS) and reached several results: There is a statistically significant difference at the mean level (? = 0.05) between the average scores of the experimental group and the control group in the application of the achievement test of Islamic education for the experimental group. Also, there is a statistically significant difference at the mean level (? = 0.05) between the average scores of the experimental group student and the scores of the control group students in the application of the orientation of the students towards Islamic education for the experimental group. According to the findings of the study, it recommends encouraging teachers to use the differentiated instruction strategy in their teaching, conducting training courses and workshops for teachers, incorporate the differentiated instruction strategy into modern teaching methods in teacher guides.