This study combined parent and observational measures to examine the association between aberrant sensory features and restricted, repetitive behaviors in children with autism (N=67) and those with developmental delays (N=42). Confirmatory factor analysis was used to empirically validate three sensory constructs of interest: hyperresponsiveness, hyporesponsiveness, and sensory seeking. Examining the association between the three derived sensory factor scores and scores on the Repetitive Behavior Scales--Revised revealed the co-occurrence of these behaviors in both clinical groups. Specifically, high levels of hyperresponsive behaviors predicted high levels of repetitive behaviors, and the relationship between these variables remained the same controlling for mental age. We primarily found non-significant associations between hyporesponsiveness or sensory seeking and repetitive behaviors, with the exception that sensory seeking was associated with ritualistic/sameness behaviors. These findings suggest that shared neurobiological mechanisms may underlie hyperresponsive sensory symptoms and repetitive behaviors and have implications for diagnostic classification as well as intervention.