Though a number of studies addressed the current needs in EFL teachers' training, a main research gap yet to be addressed is investigating the efficacy of the professional development of in-service teachers using an instructional model and its actual impact on students. Through using three instruments -designed by the author- that included: (a survey of EFL teaching skills, a teacher knowledge test, a digital literacy skills scale, a teacher performance assessment analytic rubric), this study attempted to determine the impact of ASSURE model on EFL in-service preparatory teachers teaching skills and digital literacy skills. The results indicated that z-values of the teachers' knowledge test, teachers' digital literacy skills scale and teachers' performance assessment rubric were significant. ASSURE model proved to be helpful in developing EFL preparatory teachers teaching skills and digital literacy skills.