The purpose of this study was to examine the efficacy of the token economy system in reducing physical aggression, property destruction, and disruptive talk in an adolescent diagnosed with autism spectrum disorder. The participant, age 15, met the enrollment criteria of a residential school designed to address the behavioral and academic needs of children with developmental disabilities. This study used quantitative, single subject treatment reversal design. The participant’s behavior was observed and data was collected in Phase I, Baseline, “A” (one week), Phase II, Intervention, “B” (seven weeks), and Phase III, Return to Baseline, “A” (one week). In Phase I, Intervention, “A” the variability of the frequency of targeted behaviors included: physical aggression was 0 to 10, property destruction was 0 to 6, and disruptive talk was 0 to 7. In Phase II, Intervention, “B” the variability of the frequency of targeted behaviors included: physical aggression was 0 to 8, property destruction was 0 to 5, and disruptive talk was 0 to 40. In Phase III, Return to Baseline, “A,” the variability of the frequency of targeted behaviors included: physical aggression was 0 to 9, property destruction was 0 to 2, and disruptive talk was 0 to 15. Interpretation of the results indicated instability in the variability of the frequency of all targeted behaviors, as the token economy did not serve as an effective method in modifying the behavior of the participant.