Physical activity must be of a minimum intensity to improve health and fitness. However, exercise intensity can be complicated to monitor so subjective rating of perceived exertion (RPE) scales are often used during physical activity participation and exercise tests. Individuals with intellectual disabilities (ID) may have additional difficulty monitoring exercise intensity due to limitations in cognitive functioning. For this reason, RPE scales may be especially useful for this population. The purpose of this study was to investigate the ability of adults with ID to rate perceived exertion through examining the relationships among heart rate (HR), workload (WL), and RPE during a graded walking protocol. Eighteen adults (10 males, 8 females) with mild MR (34.7 ± 12.3 years) volunteered to participate. Participants wore heart rate monitors during the protocol and the Children's OMNI-walk/run Scale was used to rate perceived exertion. The OMNI Scale has a numerical range of 0-10 and includes pictorial and verbal descriptors. Treadmill speed was held constant at 1.5mph while incline increased by 2% every 2 minutes until the participant stopped or completed the protocol (i.e., reached 20% incline). RPE and HR values were obtained every 2 minutes. Spearman's rho were calculated for each participant to examine the relationship between RPE and HR, and RPE and WL. Further, regression analyses were conducted to examine the ability of HR and WL to predict the variability in RPE for each participant. Significant positive correlations existed between RPE and HR for 10 of the 18 participants, and significant positive correlations existed between RPE and WL for 11 of the 18 participants. One participant displayed significant negative correlations between RPE, HR, and WL. Two participants exhibited no relationship because they selected the same RPE value at every WL. R-squared values indicated that the variance in RPE that could be predicted by WL ranged from 8.3%-97.6%, and the variance in RPE that could be predicted by HR ranged from 1%-93.8%. The results imply that the majority of individuals with ID were able to provide a subjective estimate of exercise intensity during a graded walking protocol. However, results were variable and some individuals selected RPE values that did not correspond with HR or WL. The OMNI Scale may be a useful tool for monitoring exercise intensity in individuals with MR, however, for safety purposes additional objective measures should be employed. More research is needed in this area to promote safe and effective exercise practices. Keyword(s): adapted physical activity, exercise/fitness, research