This study aimed to examine the neuropsychological correlates of child patients diagnosed with ADHD, autism spectrum disorder (ASD), or comorbid ASD + ADHD through a multidisciplinary ASD evaluation clinic. Patients completed standardized tests of intellectual, attention, social-affective/cognitive, and executive functioning; and a semi-structured assessment commonly used for autism diagnosis. The majority of patients were medicated for ADHD concerns during testing. Parents and teachers also completed inventories of day-to-day social and attentional functioning. Group effects were found across objective social measures but not across related respondent-ratings. In contrast, group differences were observed in parent-ratings of attention difficulties, but not on standardized tests of attention or executive functioning. Findings underscore importance of integrating objective and functional measures when assessing ASD and/or ADHD.