The purpose of this study was to investigate the effect of critical thinking-infused paragraph writing instruction on enhancing university first-year L2 students’ intellectual traits. The study involved two randomly selected first-year Social Science stream classes. The researchers employed the embedded design in the study because they mainly used quantitative data augmented by qualitative data. The researchers analyzed the questionnaire data and the interview data using the one-way between groups ANCOVA and thematic analysis method respectively. The finding of the questionnaire data analysis indicated that participants in the treatment group were better in their intellectual traits scores. The result of the interview data analysis also revealed that participants in the treatment group had a better interest in using elements of thought and intellectual traits after the intervention. Hence, integrating critical thinking instruction into APW lessons needs to be considered among all stakeholders to enhance university first-year EFL students’ intellectual traits. Keywords: Argumentative paragraph; critical thinking; instruction; intellectual traits; university first-year students.

The purpose of this study was to investigate the effect of critical thinking-infused paragraph writing instruction on university first-year students’ argumentative paragraph writing performance. In order to achieve the purpose, two randomly selected intact classes with 31 and 32 participants were involved in the study as a non-treatment group and a treatment group respectively. The treatment group was provided with critical thinking-infused paragraph writing instruction, but the non-treatment group received a conventional paragraph writing instruction. The embedded design was employed in the study since it was mainly conducted using quantitative data gathered through tests before and after the intervention, and a semi-structured interview was also employed to gather data about the treatment from some randomly selected participants in the treatment group. The quantitative data were entered into SPSS version 20 and analysed using descriptive statistics and one-way between groups ANCOVA while the qualitative data were analysed by narrating the reactions of the randomly selected participants using words. The one-way ANCOVA results for argumentative paragraph writing performance scores F (1, 60) = 106.555, p = 0.000, partial Eta squared = 0.640) showed that there was statistically a significant difference between the non-treatment and the treatment groups in their argumentative paragraph writing performance due to the intervention (Critical thinking-infused paragraph writing instruction). The interview analysis result also revealed that the intervention guided participants in the treatment group to perform better while they wrote argumentative paragraphs. Thus, it was recommended that EFL instructors, curriculum (syllabus) designers, and material developers need to integrate critical thinking instruction into argumentative paragraph writing lessons in order to promote first-year students’ argumentative paragraph writing performance.