Mediating role of students’ self-assessment in the relationships among EFL students’ L2 grit, motivation, and willingness to communicate

L2 grit, self-assessment, motivation, and willingness to communicate (WTC) are essential psychological and affective factors influencing English as a Foreign Language (EFL) learners' success. Previous research has examined these factors individually; however, the complex interrelationships among them, particularly the mediating role of self-assessment, remain underexplored. Using a quantitative research design, this study employed structural equation modeling (SEM) to analyze how L2 grit associates with motivation and WTC, with self-assessment serving as a mediating variable. Data were collected from 356 Iranian EFL learners at intermediate and advanced levels using four validated scales: the L2 Grit Scale, Motivation Questionnaire, Core Self-Evaluation Scale, and WTC Scale. SEM was employed to analyze the direct and indirect associations involving L2 grit, motivation, and WTC, while exploring the potential mediating role of self-assessment. The SEM analysis indicated a positive association between L2 grit and motivation (β = 0.55, p < 0.001), with partial mediation by self-assessment observed in this association (β = 0.09, p = 0.03). Furthermore, a significant positive relationship was observed between motivation and WTC (β = 0.54, p < 0.001). These findings contribute to the theoretical frameworks of self-determination theory (SDT), control-value theory (CVT), and grit theory (GT), emphasizing the role of psychological resilience and self-regulation in language learning. The study suggests that incorporating self-assessment practices into EFL curricula could enhance both motivation and communication skills, thereby improving language acquisition outcomes.