The instructional value of rubrics for promoting student learning and aiding teacher feedback to student performance has been extensively researched in the educational literature. There is, nonetheless, a dearth of studies on students' rubric use in second/foreign language contexts, and fewer studies have investigated the factors affecting rubrics' effectiveness for promoting student learning. The paper reports a classroom-based inquiry into students' perceptions of rubric use in self-assessment in English as a Foreign Language context and the factors moderating its effectiveness. Eighty students at a Chinese university participated in the study. The data collected included their reflective journals and six case study informants' retrospective interviews. Results showed that the rubric was perceived as useful for fostering the students' self-regulation by guiding them through the stages of goal-setting, planning, self-monitoring and self-reflection. Both within-rubric and rubric-user factors were identified as affecting the rubric's effectiveness in student self-assessment. The findings are discussed with reference to the design features of rubrics. Implications are drawn for formative rubric use in student self-assessment.