Adaptive functioning, or the suite of skills essential for real-world, day-to-day functioning, includes daily living, communication, and socialization abilities. Even in the absence of co-occurring intellectual disability (IQ < 70), difficulties in adaptive functioning are prominent in autism spectrum disorder (ASD). Further, ASD individuals without co-occurring intellectual disability (ID) demonstrate a gap between IQ and adaptive functioning, which widens with age. Existing studies of IQ-adaptive functioning discrepancies have characterized predominantly male ASD samples; thus, whether the gap is demonstrated in ASD females is unknown. To probe sex- versus diagnosis-specific differences in adaptive functioning in ASD, we characterized adaptive functioning using the Vineland Adaptive Behavior Scales, Second Edition in 177 non-ID (IQ > 70) ASD (females = 75, males = 102), and 178 typically developing (TD) (females = 87, males = 91) youth, aged 8-17 years. We examined whether each group evidenced a gap between full-scale IQ and adaptive skills and its associations with age. ASD youth evinced significantly lower adaptive skills and a significantly greater IQ-adaptive functioning gap than their same-sex TD peers. In this cross-sectional sample, the increase in the IQ-adaptive functioning gap with age was of similar magnitude for ASD males and females, but only reached statistical significance in males. We discuss unique implications the profound IQ-socialization skills gap in particular may have for ASD females.