Due to the potent role of critical thinking in learners’ academic success and its connection with factors conducive to learning such as argumentation ability, the present study seeks to primarily probe the correlation between Iranian EFL learners’ critical thinking ability and their argumentative writing achievement, and investigate the predictability of the students’ argumentative writing achievement based on their scores on critical thinking scale. Furthermore, the effect of gender on Iranian EFL learners’ argumentative writing achievement was investigated. In so doing, 'Watson-Glaser Critical Thinking Appraisal' (2002) as well as an argumentative writing assignment was employed, and the participants of the study included 178 EFL learners in three universities in Mashhad, Iran. Structure Equation Modeling (SEM) was utilized to analyze the data. The results substantiated the positive correlation between critical thinking ability and argumentative writing revealing that these two variables significantly and positively related to each other among the predictors (subscales of the critical thinking) of argumentative writing, inference, assumptions, arguments were the stronger predictors. Finally, gender was not found to significantly affect Iranian EFL learners’ argumentative writing achievement. The conclusions and implications of this study are pointed out with reference to foreign language teaching context.

Reading comprehension (RC) and critical thinking (CT) are the two basic cognitive skills that should be developed through involving language learners in a carefully planned instruction. Multiple intelligences (MI) instruction may assist learners in developing RC and CT in L2 education. This study probed the effect of MI-based reading instruction on the Iranian EFL learners’ RC and CT skills. In so doing, it compared the effectiveness of an MI-based reading instruction with a traditional one. To this end, 4 intact classes from several English language institutes, comprising 56 Iranian intermediate-level EFL learners, were selected and randomly assigned to MI-based (experimental) and traditional (control) groups. A multiple- choice RC test, a reading summary test, and the Watson-Glaser Critical Thinking Appraisal test were used as the instrumentations to collect data on the participants’ RC and CT. Analysis of covariance revealed a significant effect for the MI-based reading instruction. Furthermore, the RC scores increased more significantly in the MI-based group in comparison to the traditional one. However, the CT scores did not significantly improve in both groups. There was also no statistically significant difference in the CT scores between the two groups after the treatments. Iranian EFL educators are, then, encouraged to develop MI-based lessons and activities for diverse students and take explicit instruction for the enhancement of CT skills in EFL reading courses.