This paper studies responses to high-stakes incentives arising from early ability tracking. We use three complementary research designs exploiting differences in school track admission rules at the end of primary school in Germany’s early ability tracking system. Our results show that the need...

We show that in school systems with grade retention or redshirting, birth cohort size is negatively related to the grade-level share of students who are too old for their grade. This compositional effect gives rise to an upward bias in estimates of class size effects based on commonly used...