Metadiscourse has been recognized as an important aspect of effective persuasive discourse. In this study, we explore how metadiscourse features are deployed by 34 EFL undergraduate students to make their non-discipline persuasive texts effective. We find that students grasp at least some of the metadiscourse resources available to them, but are relatively limited in rhetorical sophistication. In fact, transitions, frame markers, code glosses and hedges were found to be critical elements contributing to student writing quality. The findings also show that both frequency and diversity of frame markers are positive predictors of overall writing quality. We also investigate the linguistic forms of metadiscourse used by the students to project stance in their writing. The students were found to have difficulty handling the range of stance construction they could take, and this was unfortunately couched in single-word modal verbs. Teachers should make the metadiscourse features of persuasive writing explicit to students to assist them in making stronger arguments.