Searching for differences and discovering similarities: Why international and resident second-language learners’ grammatical errors cannot serve as a proxy for placement into writing courses

•This study used a mixed methods design to compare the writing of international and resident second-language writers.•The study includes both quantitative comparisons of participants’ scores and qualitative comparisons of participants’ grammatical errors.•Results reveal more similarities than differences in the two groups’ grammatical errors, in contrast with previous research.•Findings challenge reductive views of L2 writing, especially for placement testing purposes.

Recent research has drawn attention to differences in the writing produced by international second-language writers and U.S. resident second-language writers, with implications for placement into college writing courses. Initially designed to complement the literature through the discovery of different types of grammatical errors in the writing produced by these two groups of learners, the current study instead challenges previous research by noting how similar the two groups’ grammatical errors are when examined in detail. Findings suggest that when groups are controlled for writing proficiency and first language, noticeable differences across the groups diminish. The study's findings call into question placement decisions for resident second-language writers, as well as the value of relying on differences in grammatical errors to distinguish the two groups. Findings can assist writing program administrators, placement test administrators, and writing instructors who need to accommodate both international and resident second-language learners.