Two widely used forms of stratification are grade repetition and early tracking. While the decision to retain a student al a given grade or to place a student in a less academically-oriented programme is made primarily on the basis of performance, research suggests that students' background characteristics can also play a role in the likelihood that students are sorted into different grades and programmes (Agasisti and Cordero, forthcoming: van de Werfhorsl and Mijs, 2010). Volume II provides a more in-depth examination of the association between student performance and school-level resources, learning environments and stratification policies and practices, and of how they reflect the level of equity in a system.