This study investigated the relationship between restricted, repetitive behavior (RRB) and anxiety in a sample of adults with intellectual disability (ID). Six regression analyses were conducted. Predictor variables were age, severity of autism spectrum disorder (ASD) symptoms, level of adaptive functioning, and anxiety; RRB (in general and specific subtypes) was the criterion. Together, the four predictor variables accounted for a significant proportion of the variance in total RRB, Stereotypic Behavior, Compulsive Behavior, Ritualistic/Sameness Behavior, and Restricted Interests. Self-injurious behavior (SIB) was the only subtype of RRB in which the results of the regression analysis were not significant. Anxiety was found to independently account for a significant proportion of the variance in total RRB, Compulsive Behavior, and Ritualistic/Sameness Behavior. This suggests that changes in RRB in general and in particular subtypes, specifically compulsive behavior and ritualistic/sameness behavior, may be observable indicators of anxiety in adults with ID. Overall, this study highlights the need for more research on RRB in general and on the relationship between RRB and anxiety, especially across different populations and settings
