Five tests commonly used to determine the reasoning abilities of autistic children vary widely in length of time to administer. DSM-IV criteria were used to determine if shorter measures of reasoning abilities could provide the same information as longer measures in less time, and also to determine whether the usefulness of this information could be improved with the addition of adaptive behavior scores. There were 282 autistic and non-autistic participants ages 4 to 19 years from a national database containing scores from the Stanford-Binet Intelligence Scales-Fifth Edition, Peabody Picture Vocabulary Test-Third Edition, Raven's Colored Progressive Matrices and the Vineland Adaptive Behavior Scales-Second Edition. Results suggest that the shorter Peabody and Raven's could provide similarly reliable results when compared to the longer Stanford-Binet for autistic and non-autistic children. The usefulness of information was enhanced with the inclusion of Vineland scores. The limitations of the study; as well as future research was discussed.