This study explores interactional metadiscourse in successful and less-successful (i.e., A- vs. B-graded) argumentative essays written by Chinese ESL university students, and how these ESL writers compare with high-rated L1 students. The analysis is based on three corpora of student writing: 25 successful ESL essays, 25 less-successful ESL essays, and 25 successful L1 English papers. Using Hyland’s (2005a) model of interactional metadiscourse, these papers were compared to examine the extent to which successful and less-successful student-produced argumentative essays differ in their employment of stance and engagement resources. Findings of the analysis suggest that successful essays, both L1 and L2, contain significantly greater instances of particularly hedging devices than less-successful essays. For some interpersonal resources, such as boosters and attitude markers, no significant differences were found. The analysis also reveals that, unlike their L1 peers, ESL students were overwhelmingly reluctant to establish an authorial identity in their writing. The paper concludes with a few implications for L2 writing pedagogy.