The present study investigated the working memory abilities of children with attention deficit/hyperactivity disorder (ADHD) as measured by the Stanford-Binet Intelligence Scales, Fifth Edition (SBV). In a retrospective causal-comparative design, the archival data of 46 ADHD children were compared to 59 nondiagnosed children. The ADHD children scored significantly lower in measures of working memory compared to the control group. Within the ADHD group, working memory was the lowest factor score, significantly lower than three of the four other factors. Significant differences were also revealed within the working memory factor, with ADHD children displaying significantly lower nonverbal working memory scores than verbal working memory. No such differences were evident in the control group. The results are interpreted within Baddeley's working memory model. (Contains 1 figure and 3 tables.)