The present study investigated the effectiveness of a novel class-wide intervention, the Classroom Password, for increasing the academic engaged behavior of middle school students. The effectiveness of an independent group contingency was evaluated using a concurrent multiple baseline design across three seventh- and eighth-grade classrooms. Results indicated that the intervention was effective across all three classrooms in increasing students' academic engagement, or on-task behavior, as evidenced by visual analysis and moderate to large effect sizes. Decreases in disruptive behavior were also observed across all three classrooms. Off-task behavior was not substantially affected in any of the three classrooms. The intervention received mixed ratings by the classroom teachers regarding its social validity. Results of the present study suggest that the Classroom Password may be an effective class-wide intervention for increasing the academically engaged behavior and decreasing the disruptive behavior of middle school students during instructional time.