This present study identifies the most frequently used lexical bundles in argumentative essays written by L1 English and L2 Taiwanese undergraduate students and compares the use of high-frequency lexical bundles between these two groups of writers. Drawing student-produced argumentative essays from the ICNALE (International Corpus Network of Asian Learners of English) (Ishikawa, 2013), we established two sub-corpora: ICNALE-TW with 400 essays produced by L2 writers from Taiwan and ICNALE-EN as a comparable dataset with 400 essays contributed by native speakers. Based on the structural and functional taxonomy proposed by Biber and his colleagues (Biber et al., 1999), the forms and functions of four-word lexical bundles used by L1 and L2 students were manually annotated. The findings reveal that among the top 100 lexical bundles identified from the two sub-corpora, 16 lexical bundles are shared by L1 and L2 student writers and that through structural and functional analyses, both L1 and L2 writers’ lexical bundles exhibit a similar tendency, consisting mostly of verb phrases and stance related expressions. The findings presented in this study may have pedagogical implications with respect to the instruction of formulaic language in academic writing at the tertiary level.