This study focuses on the analysis of school exclusion, which underlies and causes early school leaving, in 20 schools around Porto, Portugal. It is based on the qualitative and documental study of the personal school files of 25 youth, born between 1996 and 2003, who have left school and are now in a situation of social exclusion. We created a characterization grid for these "at-risk" students, and we have picked the following categories for the analysis of their schooling paths: early detection of misalignment processes between students and school; disruptive behaviour and corrective and punitive actions by schools; individual academic paths; main pedagogical recommendations devised by schools; and the articulation mode for these measures leading up to the exclusion from school. The study allows us to understand how these educational practices, through processes marked by humiliation and disqualification, create unteachable students, as well as make them solely accountable--together with their families--for their own academic failure, thus hiding the role of the schools as promoters of silent exclusion.