Self-monitoring (SM) is a widely used intervention to address a myriad of problem behaviors exhibited by individuals with autism spectrum disorder (ASD) and other disabilities (e.g., specific learning disability). SM of performance (SMP) interventions have been effective in increasing task completion and on-task behaviors in the general education setting. However, most of the research on SM interventions has been completed in a school setting, and few have evaluated the inclusion of a peer mediator component within a SM treatment package. Therefore, the purpose of this study was to evaluate the effects of a SMP intervention on disruptive behavior and task completion in three children with ASD. This study extends previous research by incorporating a peer mediator component, including children with ASD, and implementing the intervention in a clinic setting. The results show that the SM treatment package was effective, as the level of disruptive behavior and task completion improved for all three participants compared to baseline levels.