There is no consensus about whether a teacher-centred or student-centred instructional approach is more effective for students' maths achievement. Prior studies have highlighted the role of students' maths self-concept as a predictor and mediator for maths achievement. This study examined whether instructional approaches were related to students' maths achievement and whether the relation between instructional approaches and maths achievement was mediated by students' maths self-concept. The study used a sample from the 2015 TIMSS United States national data of 4th grade teachers and students. The results of structural equation modelling indicated that student-centred instructional approach was not associated with students' maths achievement. Nor was the relation between student-centred instruction and students' maths achievement mediated through students' maths self-concept, indicating that maths self-concept is not the mechanism through which student-centred instruction was associated with maths achievement. Our study discussed the possible ways that student-centred instruction may encourage or discourage students' maths self-concept and suggestions to overcome the methodological limitation of TIMSS data.