In this study we analyzed the effects of a self-monitoring and self-monitoring plus reinforcement intervention on classroom behavior. A typically-developing high school student demonstrating difficulty staying on-task during classroom instruction was observed in three classroom settings associated with high levels of off-task behavior. During baseline, the participant was observed during typical classroom activities. Next, the participant was taught to self-monitor his on-task classroom behavior, but no additional reinforcement was provided. Finally, self-monitoring plus reinforcement was implemented, in which tangible reinforcement was provided for on-task behavior. A multiple baseline across settings design was implemented. Findings suggest that only the self-monitoring plus reinforcement intervention had a marked effect on on-task behavior.