Student engagement promotes school learning and adaptation and can be a protective factor for children who are vulnerable to school failure. A longitudinal mixed-methods study was conducted to identify individual, family and school predictors of children's school engagement as well as to explore the facilitators of and obstacles to student engagement at school amongst children with externalising problems. The sample consisted of 369 elementary school children (53.7% girls) and their parents as well as 35 teachers. Participants completed several measures to evaluate emotional and behavioural engagement at school, externalising behaviours, parental emotional support, parental involvement with the school and student-teacher relationships. Semi structured interviews were conducted with a subsample of 17 parents of children with high levels of externalising problems. Problems with externalising behaviours and student-teacher relationships were significant predictors of school engagement. Parents' reports showed that family support, positive student-teacher relationships, and positive relationships with peers are the main facilitators of school engagement in children with high levels of externalising problems. Our study highlights the role played by externalising problems in school engagement. Limitations of the study and implications for prevention research and practice are discussed.