This 5-year follow-up study examined the stability of adaptive functioning in two cognitive ability groups of children with an autism spectrum disorder (ASD). Nonverbal intelligence (NVIQ) was assessed at the time of this study and no participant changed cognitive group membership from the previous study (High NVIQ greater than or equal to 97; Low NVIQ less than or equal to 56). In each group, adaptive skills, as measured by the Vineland Adaptive Behavior Scales (VABS) composite standard score, were significantly below NVIQ. Both groups exhibited a significant decrease in the VABS composite "standard" scores over time, but analysis of VABS total "raw" scores showed a significant increase in adaptive functioning over time in the High NVIQ group with no change in the Low NVIQ group. Examining the profile of VABS age equivalent scores in each NVIQ group revealed potential suggestions for interventionists. Caregivers of the Low NVIQ group endorsed having significantly higher stress levels related to their child's level of adaptive functioning. Groups did not differ significantly in the quantity of treatment received within the 9 months preceding this study or caregiver satisfaction with intervention services. Caregivers from both groups identified a variety of school-based service needs to address their child's adaptive skill deficits.