This study aimed at enhancing Egyptian EFL second-year engineering majors' grammatical achievement and accuracy by implementing a suggested flipped learning program. Participants were thirty-six EFL engineering sophomores, and they were taught grammar according to the suggested program for ten weeks during the fall 2022 semester of the academic year 2022/ 2023. Instruments were a pre-/post grammar achievement test and a pre-/post grammatical competence test. Results of the grammatical achievement posttest revealed the study group's tangible growth in their overall grammar achievement and in their achievement of each grammar sub-skill. Grammatical competence posttest results proved the remarkable improvement in the participants' ability to use accurate grammatical structures in written as well as in spoken tasks. Therefore, it was concluded that flipping grammar instruction resulted in significant progress in the participants' grammatical achievement and competence. Recommendations were made to flip the instruction of other language skills and investigate its impact on fostering these skills among students in varied educational settings.