How teacher-student collaborative assessment relates to L2 writing self-efficacy: insights from Chinese EFL learners.

Objective: Teacher-student collaborative assessment (TSCA) has attracted increasing attention as a participatory assessment approach in L2 writing, yet its relationship with writing self-efficacy remains underexplored, particularly in secondary-level EFL contexts. This study aimed to examine whether TSCA was associated with changes in students' L2 writing self-efficacy and whether different patterns emerged across gender and internally defined pretest performance subgroups. Methods: A quasi-experimental pretest-posttest design was implemented with two intact Grade 10 classes in a Chinese senior high school. One class received TSCA-based writing instruction, whereas the other followed a traditional teacher-centered assessment approach. Writing self-efficacy was measured using an adapted questionnaire, and supplementary qualitative data were collected through semi-structured interviews. Quantitative data were analyzed using descriptive statistics and t-tests, while interview data were examined through thematic analysis. Results: The experimental group showed stronger improvement patterns in overall writing self-efficacy than the control group, including improvement in both task self-efficacy and skill self-efficacy. Within the experimental group, no statistically significant gender difference was observed in the subgroup comparisons, whereas differences were observed across internally defined pretest performance subgroups, with the higher pretest-performing subgroup showing a stronger improvement pattern than the lower pretest-performing subgroup. The interview findings provided supplementary insight into how students perceived the TSCA process and how these perceptions differed across subgroups. Conclusion: The findings suggest that, within the present instructional context, students in the TSCA group showed more favorable patterns of self-efficacy development than those in the comparison group. This pattern was observed in overall writing self-efficacy and in both subdimensions, although subgroup findings were exploratory and should be interpreted cautiously. Given the quasi-experimental design, the single-school sample, and the limited subgroup analyses, the results should be understood as context-bound rather than as strong causal evidence.