The relationship between adaptive functioning and autism symptomatology was examined in 1,089 verbal youths with ASD examining results on Vineland-II, IQ, and measures of ASD severity. Strong positive relationships were found between Vineland subscales and IQ. Vineland Composite was negatively associated with age. IQ accounted a significant amount of the variance in overall adaptive skills (55%) beyond age and ASD severity. Individuals with ASD demonstrated significant adaptive deficits and negligible associations were found between the level of autism symptomatology and adaptive behavior. The results indicate that IQ is a strong predictor of adaptive behavior, the gap between IQ and adaptive impairments decreases in lower functioning individuals with ASD, and older individuals have a greater gap between IQ and adaptive skills.