Students presenting oppositional behaviors often display lower behavioral and emotional engagement in class as compared to their peers. Moreover, children in general are known to be deeply affected by their relationships with teachers while in school. It is therefore possible that such relationships could also influence the engagement of students presenting higher levels of oppositional behavior. As a way of verifying this hypothesis, the present study investigated the contribution of students’ levels of oppositional behavior to their behavioral and emotional engagement in literacy. Furthermore, it examined whether these relationships were different for boys and girls, or changed as a function of two components of student-teacher relationships: closeness and conflict. Three hundred and eighty five third and fourth grade students and their teachers participated in the study. Two series of linear regressions were conducted. Findings indicate that students who presented higher levels of oppositional behavior showed lower behavioral engagement than their peers. Moreover, students who had close relationships with their teachers reported higher behavioral engagement. Although closeness in student-teacher relationships protected students from behavioral disengagement, students with higher oppositional behaviors were less protected than students who presented lower levels of oppositional difficulty. Having a warm relationship with a teacher was also more beneficial for the behavioral engagement of girls, whereas a high level of conflict between student and teacher was more harmful for the emotional engagement of boys. This was deemed to be true whether the boys or girls presented high levels of oppositional behavior or not. Overall, our findings highlight the importance of the student-teacher relationship in fostering all students’ engagement in school.