["Autism Research, EarlyView. ", "\nABSTRACT\nRestricted and repetitive behaviors (RRBs) are one of the diagnostic criteria for autism spectrum disorders (ASD), as well as being found in the general population. The current study aims to explore the psychometric properties of the Turkish self‐report and informant‐report forms of the Repetitive Behaviors Questionnaire‐3 (RBQ‐3) for individuals with ASD and the general population across the lifespan. A series of factor‐analytic methods was employed to analyze data from study groups with diverse characteristics. A total of 1803 individuals participated in the study. Bayesian confirmatory analysis, confirmatory factor analysis, exploratory structural equation modeling, the average variance extracted, and measurement invariance analyses were performed to provide evidence of construct validity for the Turkish RBQ‐3's in both self—and informant forms. In addition, the reliability of the Turkish RBQ‐3 scores was evaluated using Cronbach's alpha, McDonald's omega, and composite reliability. In conclusion, the adapted self‐report and informant‐report forms of the RBQ‐3 demonstrate strong psychometric properties for assessing RRBs in both individuals with ASD and the wider population across the lifespan in Türkiye. The Turkish RBQ‐3 offers a valuable tool for Turkish researchers and clinicians, advancing the understanding of RRBs.\n"]