This study investigates the application of machine translation (MT) in an EFL writing class and its impact on lower proficiency level writers. Theoretically grounded in the social nature of learning, the MT-based writing class is applied to students in four steps: planning, drafting with MT, revising MT output, and individual writing with MT. The peer-editing process and the teacher's guidance have been found to be critical factors in terms of enhancing students' metalinguistic awareness at both the micro-level and macro-level revisions of MT output. Additionally, by gaining confidence and motivation, the students become more autonomous and self-directed. The results of this study provide insights into how an MT-based EFL writing class can be conducted successfully by including peer and teacher feedback and thus result in MT being viewed as an effective tool, rather than being considered taboo for helping lower level EFL learners in writing.