Linguistic Distance and Syntactic Complexity in L2 Writing: A Dependency‐Based Analysis Across 17 L1 Backgrounds

ABSTRACT

Syntactic complexity is a central dimension of second language (L2) writing proficiency, yet it remains underexplored how it varies across learners from diverse first‐language (L1) backgrounds and whether such variation can be explained by linguistic distance. Drawing on a corpus of English writing produced by L2 learners from 17 L1 backgrounds, this study examines the effect of L1 background on syntactic complexity using Mean Dependency Distance (MDD) and Mean Hierarchical Distance (MHD) and tests the explanatory power of linguistic distance. The results show that L1 background has a significant effect on syntactic complexity in L2 writing. MDD and MHD are positively correlated, suggesting an integrated property of syntactic organization. Cluster analysis identifies three relatively distinct groups among the 17 L1 backgrounds, indicating that patterns of syntactic complexity are better captured by data‐driven groupings than by traditional language classifications. Regression analyses show that linguistic distance significantly predicts both measures, but the effect is substantially stronger and more robust for MHD ( p  = 0.007, R ²  = 0.55) than for MDD ( p  = 0.069, R ²  = 0.435), with structural distance based on linguistic features (WALS) outperforming genealogical distance (eLinguistics) in explaining the observed variation. These findings indicate that cross‐L1 variation in syntactic complexity is shaped primarily by structural similarity rather than evolutionary relatedness. Pedagogically, the findings suggest that L2 writing instruction should attend to learners’ L1 backgrounds, particularly in the teaching of hierarchical structures, and that writing assessment frameworks may benefit from considering cross‐linguistic differences rather than applying uniform complexity expectations, thereby offering empirical support for linguistically responsive writing instruction.