In order to gain physical fitness and health, exercise must be performed at a sufficient level of intensity. Exercise intensity can be monitored with rated perceived exertion (RPE) scales to promote safe and effective programming. The usefulness of the Children's OMNI Scale as a subjective measure of intensity for adults with intellectual disabilities (ID) was examined. Heart rate, workload, and RPE were monitored during a progressive walking protocol on a motorized treadmill in 18 adults with ID. Statistical analyses on individual data revealed that significant positive relationships among RPE, heart rate, and workload existed in most participants. However, results were highly variable. Results imply that some individuals with ID are able to provide a subjective estimate of exercise intensity while others may not be able to report accurately. The findings have significant practical implications for exercise programming in this population. (Contains 3 tables and 3 figures.)