One challenge teachers have when teaching mixed-ability classrooms is ensuring that each student is appropriately supported and challenged based on their current ability. Tiering is an instructional strategy proposed in the Differentiated Instruction approach to address this issue. This article explores how an English reading course that tiered the content, process, and product affected the reading comprehension of ninth grade EFL students. The three elements were tiered to serve three groups of students--basic, grade-level, and advanced. Two parallel pretest and posttest were used to collect the data. The positive effects of the tiered instruction on the students' reading comprehension in this study suggest further implementation of tiered instruction in other EFL classrooms. Further research should explore how tiered instruction functions with different learner demographics and in other language skill settings.