This paper uses extensive student-level micro databases of three international student achievement tests to estimate heterogeneity in the effect of external exit examinations on student performance along three dimensions. First, quantile regressions show that the effect tends to increase with student ability—but it does not differ substantially for most measured family-background characteristics. Second, central examinations have complementary effects to school autonomy. Third, the effect of central exit examinations increases during the course of secondary education, and regular standardised examination exerts additional positive effects. Thus, there is substantial heterogeneity in the central-examination effect along student, school and time dimensions.