The current study investigated the impact of an interventionist model of dynamic assessment, using a repetitive process of pretest-teach-posttest design, on Iranian EFL learners’ reading comprehension and classroom engagement. To this end, 40 intermediate participants were selected through convenient sampling from among the English majors of a university in Kerman, Iran, and assigned to two control and experimental groups, each including 20 students. Then, during 4-month period, the experimental group was exposed to reading comprehension class, using an interventionist model of DA, while the control group did not receive ant dynamic assessment program. At the end of the treatment, the participants’ scores on the pretest and post-test were statistically compared. The obtained results revealed that the experimental group significantly outperformed the control group on the scales of reading comprehension skill. A change was also observed in the classroom engagement of the experimental group, but not for the control group. Indeed, the results showed that dynamic assessment can boost participants' performance in a practical and effective way, not only in terms of reading performance but also in terms of motivating more classroom engagement among EFL learners. This finding has implications for teachers to design more efficient courses which are the ultimate goal of education.