– The results showed no direct school composition effects with respect to prior achievement, SES, ethnicity and sex on math achievement.
– Mean school prior achievement seems to positively affect initially high achievers.
– The proportion of minority students in school seems to negatively affect students speaking a non-European language except for Turkish, Arabic or Berber at home.
– Schools with a high mean prior achievement or a high mean SES keep in regular contact with their students’ parents and this, in turn, appears to enhance students’ math achievement.
– The results of the model with all the student variables revealed that almost all of them – except for the interaction term of month of birth and being a year ahead, and school well-being – appeared to be significantly associated with math achievement at the end of second grade.