Introduction. Classroom misbehavior is a major source of classroom-wasted time and a situation that negatively interferes with students’ opportunity to learn.Method. The present study investigated the relation between 5th through 9th grade perceived Portuguese teacher’s classroom management, teacher’s perceived time spend with misbehavior, teacher’s self-efficacy, and teacher’s perceived classroom misbehavior. A conditional process analysis of the relation between teacher’s classroom management and teacher’s perceived classroom misbehavior with mediator and moderator variables was tested.Results. Generically the results show that (1) teachers who perceive themselves as more controllers of students’ behaviors tend to perceive less misbehavior in the classroom; (2) that both teacher’s self-efficacy efficacy (TSE) and time spent with classroom misbehavior (TSMisb) are better predictors of classroom misbehavior than the classroom behavior management style; (3) both TSE and TSMisb fully mediate the relation between classroom management style and classroom perceived misbehavior.Discussion and Conclusion. Teachers must, therefore, learn the specific behaviors that more likely optimize the available instructional time and reduce time and energy wasted with students’ misbehavior.