Attentional difficulties are associated with a number of different pediatric clinical disorders, including attention deficit hyperactivity disorder (ADHD), learning disabilities (LD), and traumatic brain injury (TBI). Further, two cognitive functions dependent upon attention, learning and memory, are characteristic deficits in LD children, and have been documented as correlated weaknesses in ADHD and TBI populations. However, few investigations have examined the relation between these cognitive functions, in terms of understanding the respective contributions of attention, learning, and memory deficits in the clinical groups indicated above. In the present study, a measure of attention, the Gordon Diagnostic System (GDS) was compared to a measure of learning and memory in children, the Wide Range Assessment of Memory and Learning (WRAML), in ADHD, LD/ADHD, TBI, and typically-functioning Control groups (aged 9--14 inclusive, N = 25 per group). The purposes of this comparison were a) to determine the correlation between the GDS and learning and memory subtests thought to have a strong attentional component, and b) to examine how performance profiles on the various measures would discriminate among clinical groups, and predict group classification. Results of the correlational analysis indicated relations among the measures along the lines of visual and verbal working memory, versus the expected attention/memory dichotomy. The discriminant analysis revealed that the LD/ADHD group demonstrated significantly more difficulties on both verbal and visual working memory tasks, compared to the other groups, and that visual working memory tasks primarily separated the ADHD and TBI groups from the Control group. These findings were discussed in terms of the importance of considering working memory as a significant factor in attentional functions of children with ADHD, LD, and TBI.