Syntactic Complexity Measures and their Relationship to L2 Proficiency: A Research Synthesis of College-level L2 Writing

In this study I evaluate the cumulative evidence on the use of syntactic complexity measures as indices of college‐level L2 writers' overall proficiency in the target language. Based on a synthesis of twenty‐five studies, I arrive at several substantive findings. First, I conclude that the relationship between L2 proficiency and L2 writing syntactic complexity varied systematically across studies depending on whether a second or a foreign language learning context was investigated and whether proficiency was defined by programme level or by holistic rating. Second, aggregating available cross‐sectional findings, I propose critical magnitudes for between‐proficiency differences in syntactic complexity for four measures. Finally, I interpret the limited longitudinal evidence to suggest that an observation period of roughly a year of college‐level instruction is probably needed for substantial changes in the syntactic complexity of L2 writing to be observed. I conclude the paper by discussing implications of these findings for future primary research.