This study aimed to investigate the effect of Lexically-Based Language Teaching on writing proficiency among junior EFL university students in Iran. Two university classes, including sixty male and female students (N = 60), were selected and assigned equally to experimental and control groups using the convenient sampling procedure. At the onset of the study and to determine the homogeneity of the groups, the groups took the Key English Test. Before experimental intervention, a pretest, in the format of an essay writing task, was given to both groups. The results of the pretest indicated that the experimental and control groups were similar in terms of general writing proficiency, lexical resources subsection, and grammatical range and accuracy subsection. While the participants in the experimental group were taught based on practices and activities which underline the lexical approach to present essay writing, their counterparts in the control group were taught based on conventional techniques to perform the same writing task. At the end of the experiment, both groups took the posttest which was similar to the pretest in general format. The researchers used the One-Way Analysis of Covariance to compare mean scores attained by the two groups on the posttest with regard to general writing proficiency along with lexical resources and grammatical range and accuracy subsections of writing. The SPSS program, version 20, was used for this purpose. The results indicated that lexically-based language teaching has a statistically significant effect on both general writing proficiency and the lexical resources subsection of posttest writing. However, no statistically significant effect was observed concerning the grammatical range and accuracy subsection of the writing. The findings suggest implications for English language teachers, material developers, and syllabus designers.
