Is doing your homework associated with becoming more conscientious?

•More effort in students' homework is associated with a more positive development in conscientiousness.•Effects remain stable after controlling for differences between students increasing and decreasing their homework effort.•Associations are found for self-reported and parent-reported personality.

Research has shown that sustained homework effort enhances academic performance and that students' conscientiousness is a powerful predictor of students' homework effort. But does homework-as homework proponents claim-in turn also influence the development of conscientiousness over time? In the present study, we examined whether students' homework effort in two subjects (i.e., mathematics and German) was associated with inter-individual differences in students' development of conscientiousness in the early years of adolescence. Bivariate change models with a total of N = 2760 students revealed that homework effort and conscientiousness were systematically related over time (Grade 5 to Grade 8). Most importantly, students who invested more effort in their homework showed more positive development in conscientiousness.