The purpose of this study was to explore whether film-based Dynamic Assessment (DA) could affect English writing of Iranian deaf children. Ten students studying in a school for the deaf took part in the study. The participants’ writing ability was measured prior to the treatment and the errors which were identified. A series of meditating activities were designed and implemented during a three-month treatment. After the treatment, a writing posttest was administered. The results of the paired samples t-test revealed that using film-based DA had a significant impact on the English writing of the participants. The results of the structured interviews showed that almost all students had positive attitudes towards the use of films during the DA procedure.