This study describes policies and practices implemented in 12 high schools (Quebec, Canada) that more or less effectively leveraged extracurricular activities (ECA) to prevent dropout among vulnerable students. Following an explanatory sequential mixed design, three school profiles ("Effective," "Ineffective," and "Mixed") were derived based on quantitative student-reported data. Qualitative interviews with frontline staff revealed that in "Effective" schools, ECA had a unique overarching goal: to support school engagement and perseverance among all students, including vulnerable ones. Moreover, in these schools staff had access to sufficient resources--human and material--and implemented inclusive practices. In "Ineffective" schools, ECA were used as a means to attract well-functioning students from middle-class families, and substantial resources were channeled toward these students, with few efforts to include vulnerable ones. Schools with a "Mixed" profile had both strengths and weakness. Recommendations for school-level policies that bolster ECA's ability to support students' perseverance are provided.