Complexity, accuracy, and fluency in L2 writing across proficiency levels: A matter of L1 background?

While there have been studies that explored complexity, accuracy, and fluency (CAF) as an index of language proficiency, studies that comprehensively examined the inter-variations in the CAF of different L1 backgrounds across proficiency levels remain very limited. Thus, we investigated how CAF measures in L2 writing differentiate proficiency levels in six Asian L1 backgrounds. We also examined how these measures vary from one L1 background to another. A total of 3606 argumentative essays from the International Corpus Network of Asian Learners of English (ICNALE) were analyzed for 18 CAF measures. Overall results confirmed that differences exist among these measures as an index of proficiency when different L1 backgrounds are compared. The findings also provided some evidence that L2 writers who belong to typologically similar languages exhibit striking similarities in several CAF measures compared to typologically dissimilar languages. Nonetheless, the data showed that MLC, CN/T, WCR, and W/Tx are the most consistent among CAF measures in differentiating proficiency levels in each of the different L1 backgrounds. Implications for L2 writing assessment and future studies are discussed. • Complexity, accuracy, and fluency (CAF) were examined jointly as indices of proficiency. • A large sample ( N = 3606) of essays across seven L1 backgrounds were analyzed. • The findings suggest that CAF does not follow a rigid pattern of development. • CAF as an index of proficiency varies from one L1 background to another.