Restricted and Repetitive Behaviors (RRBs) are core features of Autism Spectrum Disorders (ASDs). Efforts to understand the purpose of RRBs have raised questions about the significance of the presence of RRBs in the long-term outcome of children with ASDs. Some studies have reported that the presence of RRBs during preschool years is a negative prognostic indicator for later childhood (e.g., Charman et al., 2005), while others have failed to replicate this finding (e.g., Bopp et al., 2009). This study examined the effect of RRBs on later functioning in 40 children with ASDs. RRBs were examined at ages 1-2 and 3-5 years using direct observation and parent report. These scores were used to predict cognitive functioning, adaptive abilities, and ASD symptomatology at age 8-10 years. The results suggest that RRBs observed early in the preschool period do not predict later functioning. However, when RRBs are observed at age 3-5 years, they appear to be useful prognostic indicators. Specifically, more severe preoccupations with parts of objects, sensory interests and stereotyped motor movements observed between 3-5 years of age predicted less developed cognitive and adaptive skills, as well as greater ASD symptom severity at age 8-10 years. The relationship between RRBs in the late preschool period and school age outcome is not as strong as the relationship between cognitive functioning in the late preschool period and school age outcome. However, overall, these findings indicate that exhibiting RRBs in the late preschool period does appear to be a negative prognostic indicator for school-age outcome
