This study provides new empirical evidence of birthday effects over a range of educational and socioemotional outcomes. It relies on data from the recent cycles of the Program for International School Assessment (PISA) for six European countries. Age at entry has a significant and sizeable impact on cognitive outcomes for 15-year-old students as measured in PISA. The magnitude of the birthday effects on socioemotional skills varies, but overall the results suggest that those students who enter school relatively younger have more negative relationships with their teachers and peers at school. These students also have lower intrinsic motivation and self-esteem and have less ambitious educational expectations than their peers who entered school older.