Abstract

Syntactic complexity, reflected in long sentences and multiple embedded clauses, is a key feature of high-quality academic writing as it allows writers to express complex ideas concisely and effectively. While much prior research has addressed syntactic complexity at a broad level, studies employing fine-grained measures remain limited. This study examines fine-grained syntactic complexity in research abstracts written by Vietnamese student writers, comparing them with abstracts authored by expert native English writers. Additionally, the study examines the differences between English majors and non-English majors. The analysis revealed clear differences between students and experts in both clausal and phrasal indices, alongside notable disciplinary variation. Collectively, the student writers demonstrated syntactic complexity approaching the level of expert authors, though English majors showed less advanced use of syntactic structures compared to their non-English majors. The findings contribute to understanding disciplinary and language-background influences on academic writing and highlight implications for theory and pedagogy.