Children with fetal alcohol spectrum disorder (FASD) often present with comorbid attention-deficit hyperactivity disorder (ADHD), which can complicate diagnosis and treatment planning. This study investigated the cognitive and adaptive profiles of 81 children with ADHD/FASD and 147 children with ADHD. Multivariate analysis of variance and follow-up discriminant analysis indicated that the two groups had similar profiles on the Wechsler Intelligence Scale for Children-Fourth Edition and Vineland Adaptive Behavior Scales, although the children with comorbid ADHD/FASD demonstrated significantly more impairment in verbal ability, perceptual reasoning, working memory, processing speed, and overall adaptive skills. The results suggested that when compared with children with ADHD alone, children with ADHD/FASD exhibit significantly more impaired cognitive processing and adaptive skill deficits that are essential for school success and healthy social, behavioral, and emotional functioning. Research evaluating the profiles of these groups is likely to facilitate earlier and more accurate diagnosis and intervention.