Recent research has found that the third edition of the Wechsler Intelligence Scale for Children (WISC-III), has been consistently underestimating intelligence in children with autism spectrum disorders. The WISC-III embodies a structure of analysis and interpretation that fails to incorporate advances in modern psychological theory and imposes strict timing criteria. This emphasis on time and speed of performance has had a negative differential effect on children with ASD. In order to assess whether the newest edition, the WISC-IV, has rectified the previous editions’ failings by incorporating current theory and emphasizing fluid intelligence while de-emphasizing speed, the PRI and PSI from the WISC-IV were compared with the Nonverbal index of the KABC-II. 15 high functioning school aged children with ASD were assessed on both tests and their results were compared to 15 neurotypically developing age matched controls. Although there were no significant group differences on tasks of perceptual reasoning, a significant effect of test between PRI and KABC-II scores were found for children with ASD only. In addition the ASD group still scored significantly lower than controls on the PSI, providing support for the hypothesis that previous strict time criteria has had a selective negative impact of the IQ scores of children with ASD.