Abstract-Dynamic assessment (DA) stresses the need for unifying assessment and instruction. This paper presents an interactionist model of DA to assessment in reading comprehension of 30 Iranian male students who were selected based on available sampling procedure. Data collection procedures before and after implementation of DA were done through administration of multiple-choice reading comprehension test. The results of students' performance before and after implementation of DA were calculated through t-test. The results indicate significant improvement in student performance after implementation. Finally, the null hypothesis is rejected and it is concluded that incorporation of DA as a supplement procedure to standard testing has positive effective on both test performance and learning of students.