Book excerpt: From an international comparative perspective, this third book in the prestigious eduLIFE Lifelong Learning series provides a thorough investigation into how social inequalities arise during individuals’ secondary schooling careers. Paying particular attention to the role of social origin and prior performance, it focuses on tracking and differentiation in secondary schooling examining the short- and long-term effects on inequality of opportunities. It looks at ways in which differentiation in secondary education might produce and reproduce social inequalities in educational opportunities and educational attainment. The international perspective allows illuminating comparison in light of the different models, rules and procedures that regulate admission selection and learning in different countries.