We investigated the influence of specific autism spectrum disorder (ASD) deficits in learning adaptive behaviour, besides intelligence quotient (IQ). Participated 217 school-aged: ASD (N = 115), and other neurodevelopmental disorders (OND) groups (N = 102) matched by Full-Scale IQ. We compared standard scores of Vineland Adaptive Behaviour Scale (VABS) in communication, daily living skills, socialization and adaptive behaviour composite. Pearson-correlation analysis was performed between each domain of VABS and Full-Scale, Verbal and Performance IQ, and chronological age (CA). Results indicated that impairment in adaptive behaviour within the domain of socialization skills remains a distinctive factor of ASD versus OND, independently of intellectual disability (ID). Co-occurring ID result in further debilitating effects on overall functioning, especially in ASD. CA is negatively associated with VABS scores.