Equality of opportunity is a central aim in the political agenda of many nations, andpolitical leaders consequently speak about the importance of reducing differences ineducational attainment between young persons from differing social origins. Suchdifferences are apparent at two educational steps–the transition from compulsoryschool to upper secondary and at the transition from upper secondary school totertiary institutions. Both steps have to be considered if the interest lies in attainmentof university degrees, since the outcome at the first transition affects that at thesecond. Differences in educational attainment by parental origin appear throughtwo separate mechanisms. Children from higher origins tend to perform better atschool than other children, and consequently they more than others continue tohigher educational levels. However, also among children who did perform equallywell, children from more advantaged origins more often than other children chooseto continue to higher and more academically oriented tracks. Children of immigrantstend to perform less well at school than native-born children, but given performance,they tend more than the native-born to choose to continue in academically orientedschool tracks.