Purpose This study seeks to verify if the multilevel mechanisms of self-regulated learning (SRL) processes are consistent with the analyzed data and test whether the mechanisms are mediating the effects of economic, social and cultural status (ESCS) on mathematics performance. Design/methodology/approach This study draws its data from Macao-China's Programme for International Student Assessment (PISA) 2012 study. Macao-China conducted the census of 45 schools and across those schools more than 98% of 15-year-old Macao-China students have participated in this study. Based on social cognitive theories, two aspects of SRL (motivational beliefs and prior content knowledge activation) are examined by using Hierarchical Linear Modeling. Findings At the student level of data analysis, the three SRL variables: Mathematics self-efficacy, mathematics intrinsic motivation, and familiarity with mathematical concepts are the mediating variables. Across school to student level where peer effects arise from school ESCS composition, mathematics self-efficacy is able to mediate the between-level effect of school ESCS composition on student mathematics performance. Originality/value The significance of this study is that ESCS-performance gap in mathematics amongst students can be narrowed down by introducing student's regulation of motivation and cognition into the school's mathematics curriculum. The promotion of the educational quality can be done in tandem with the improvement of educational equity for ESCS-disadvantaged students.