ABSTRACT Syntactic complexity has received significant attention in second language acquisition (SLA) research, particularly in the context of second language (L2) writing. A prevalent assumption that increased syntactic complexity signals higher L2 proficiency has driven extensive inquiry into how it reflects L2 writing development. This review synthesizes and critically evaluates existing research on syntactic complexity in L2 learners’ texts, focusing on its definition, measurement, and application. Findings reveal a pervasive over‐reliance on automated, quantitative measures, which often obscure the deeper, qualitative meaning of numerical findings and present challenges to the nuanced interpretation of syntactic complexity. The findings further demonstrate that such approaches fail to adequately capture the diverse forms of syntactic complexity and the syntactic appropriateness with which L2 learners employ elaborated syntactic structures. This article calls for a shift toward a more nuanced, multifaceted, and qualitative understanding of syntactic complexity in L2 writing, proposing the adoption of mixed‐methods approaches that allow for human interpretation of the full spectrum of syntactic complexity, including its diversity and appropriateness. Key recommendations are provided to guide the field toward a richer, more meaningful comprehension of L2 writing development that quantitative metrics alone cannot illuminate.
Sachiko Yasuda (Mon,) studied this question.