This manuscript reports on a corpus-based comparison of native and nonnative graduate students' language production in an asynchronous learning environment. Using 486 discussion board postings from a five-year period (2009-2013), we analyzed the extent to which native and nonnative university students' writing differed in 10 measures of syntactic complexity targeting the length of production unit, amount of subordination, amount of coordination, and degree of phrasal sophistication. We also compared across gender subgroups and levels of English language proficiency. Results indicated significant differences in four of 10 measures of complexity, with native speakers (NSs) engaging in more subordination and nonnative speakers (NNSs) in more coordination and phrasal sophistication. Between-group comparisons yielded no statistically significant differences between NSs and high-level NNSs, and moderate differences between NSs and low-level NNSs related to subordination. Some differences between male and female writers were found. Together these results call for interventions for enhancing the use of linguistic devices like subordination among NNS university students at tertiary levels of instruction, as well as greater attention to task design in asynchronous learning environments.