The aim of this paper is to explore the impact of the structure of the Czech education system on the development of the relationship between a student's achievement and his/her family background. It compares the strength of the relationship between student achievement and a student's family background in various stages of his/her education career (grades 4, 8 and 10) in the Czech Republic and in systems without early tracking that also exhibit high student performance (Canada, Nordic countries). In addition, the paper tests a hypothesis that systems with different levels of tracking differ not only in their structure but also in teaching methods and teachers' attitudes. The analysis was conducted on data sets from the IEA PIRLS 2001, the IEA TIMSS 1999, and the OECD PISA 2003.