The purpose of this study was to assess the effects of a dependent group contingency on eighth-grade students' heart rates. Participants were 18 male and female students. A multielement research design was used to examine the intervention effects. The intervention consisted of: (a) teacher explanation about effort; (b) students' suggestions to increase effort; (c) a chart posting the target heart rate zones goals; and (d) teacher prompts to remind students about their effort. Participants' heart rates were monitored during physical education lessons. The target rate was set between 70 and 85% of the participant's estimated maximum heart rate. The results show that participants increased their time in and above target heart rate zone from 42.1% in baseline to 62.9% during intervention. Therefore, we can conclude that the intervention was successful to increase the exercise intensity during physical education lessons.