Objective: Children with fetal alcohol spectrum disorder (FASD) can easily be misdiagnosed as having ADHD. Method: A total of 164 children were compared on cognitive and behavioral measures for four groups of children: FASD, ADHD, FASD + ADHD, and other neuropsychological disorders. Results: The ADHD group was not significantly different from the "other diagnosis" group on any of the measurements. The children with FASD were found to perform significantly worse than ADHD on externalizing problems, Full-Scale IQ, and indices of Verbal Comprehension, Perceptual Reasoning, and Working Memory. The comorbid FASD + ADHD group was significantly weaker than ADHD on verbal comprehension measures. The FASD children demonstrated significantly higher levels of atypicality and aggression relative to ADHD, and the FASD + ADHD group demonstrated significantly higher levels of hyperactivity and withdrawal relative to ADHD. Conclusion: These results indicate that children with FASD display a differential behavioral and cognitive profile that is significantly poorer than children with ADHD and other types of neuropsychological disorders.