This study used a combination of manual and automated analyses to examine how writers from various first language (L1) backgrounds make use of metadiscourse in their second language (L2) English academic writing. The Authorial Voice Analyzer (AVA; Yoon, 2017), a natural language processing tool for the analysis of interactional metadiscourse, was the main means of data extraction. Initial analyses based on a self-assembled corpus of L1 Arabic, Chinese, and French writing produced in an English as a Second Language context yielded no major differences in metadiscourse. However, this may have been influenced by the frequent presence of in-text citations used by these writers. Therefore, writing from an alternative corpus of L2 English writing, the International Corpus Network of Asian Learners of English (ICNALE) was also analyzed. This corpus produced several noteworthy results, including significant L1-related differences in the use of metadiscourse across all major functional categories (hedges and boosters, attitude markers, self-mentions and reader pronouns) by L1 Chinese, Japanese, and Korean writers.