Transferring to another school or leaving the educational system altogether has considerable consequences not only for the student who makes the decision to leave, but also for the students who stay behind. This paper aims to investigate the effects of secondary schools' mobility and dropout rates on the levels of school engagement in the persistent student population, drawing on peer effect research in engagement and dropout literature. Multilevel analysis was carried out on data collected in 2015 from 1577 non-mobile students in 25 Ghentian (Belgium) schools, who participated in the International Study of City Youth-project (ISCY). The findings suggest that schools get caught up in a vicious circle, in which higher in-mobility rates bring about lower levels of behavioral engagement in non-mobile students, making those students in turn more vulnerable for negative educational decisions like dropping out or changing schools.