Fazel Alaei - Department of English Language & Literature, University of Tehran, Iran
Shiva Kaivanpanah - Department of English Language & Literature, University of Tehran, Iran
Maedeh Mohammadi - Department of English Language & Literature, University of Tehran, Iran

lexical diversity of argumentative and narrative writings of L۲ learners, and the contribution of syntactic complexity and lexical diversity to the writing quality in the L۲ argumentative and narrative writings of EFL learners. To this end, ۴۶ pre-intermediate and intermediate Iranian EFL learners from four intact classes wrote one argumentative and one narrative essay in L۲, and one argumentative and one narrative essay in L۱ on different topics. Paired-samples t-tests revealed that lexical diversity surfaced more in the L۱ writing of the learners. Multiple linear regressions indicated that among five measures of syntactic complexity, mean length of T-unit and clauses per T-unit better predict the quality of argumentative writing. In addition, complex nominals per clause are better predictors of narrative writing quality. Simple linear regressions showed that lexical diversity is a significant predictor of L۲ writing in both genres. Based on the findings, writing instructors are advised to provide L۲ learners with explicit instruction on the use of diverse vocabulary and different syntactic structures in order to help them improve the quality of their writing.

Argumentative writing, genre, Lexical diversity, narrative writing, syntactic complexity, Writing quality