The integration of second-generation immigrants is a major challenge for European societies. Although born in the host societies, students of immigrant origin often have shorter and less successful educational careers than their native counterparts. Combining statistical and configurational methods, this book investigates whether and why, by the end of compulsory schooling, second-generation immigrants experience a disadvantage in reading, mathematics and science literacy. Migrant achievement penalties exist in all the 17 Western European countries analysed, but they are particularly large in countries where social inequalities in education are milder. This apparent paradox suggests that educational systems traditionally seen as egalitarian might not provide the best learning opportunities to students of immigrant origin. Even in comprehensive systems penalties can be large, if second-generation immigrants are segregated in low-quality schools; conversely, an early inclusion into the school system can contrast the emergence of severe achievement penalties, at least in post-war immigration countries.