The purpose of this study was to determine whether subtype differences and the role of inattention in children with attention-deficit hyperactivity disorder-combined type (ADHD-C) and ADHD-predominately inattentive type (ADHD-PI) and controls on measures of achievement, problem solving, and visual-spatial abilities are present. A secondary purpose was to evaluate the relation between ADHD symptoms and performance on visual-spatial-motor tasks. Children with ADHD-C and ADHD-PI and controls, all aged 8 to 16 years old, were compared on tests of achievement, fluid reasoning, and visual-motor skills. Children with ADHD-C and ADHD-PI performed significantly poorer on the mathematics calculation, written expression, fluid reasoning, and visual-motor tests compared with the controls. Inattention, but not hyperactivity or impulsivity, was found to significantly predict performance on these measures. The role of inattention on these tasks is important for understanding why children with both subtypes of ADHD experience significant academic problems even when performing in the average range on achievement tests.