Objective: For many neurodevelopmental disorders, the presumption is of some deviation from typical brain development in one or more functional systems. With many disorders (e.g., ADHD, LD), no hard evidence of neurological difference (MRI, CT Scan, EEG) exists. The purpose of this study was to compare the performance of children with identified neurological problems (observed) to those for whom underlying neurological differences are not identifiable (presumed). Method: This retrospective study of children, evaluated at a tertiary care facility in the southeastern United States, was restricted to children between the ages of 6 and 16 (M = 10.24; SD = 2.64) who had been administered measures of interest (n = 333). 181 had a positive finding on neurological evaluation; 152 did not. Results: These groups differed significantly for Full Scale IQ (FSIQ) (p < .001) with the observed group more impaired; therefore FSIQ was used as a covariate for additional analyses. For cognitive variables (verbal, visual motor, memory), with FSIQ controlled, only CMS General Memory Index remained significantly different between groups (p =.003); however partial eta squared is small (.03). For these groups, parents of the 271 participants completed the BASC-2, wherein ratings yielded significant differences only on Somatization (p < .001, but not typical referral concerns (e.g., hyperactivity, aggression, conduct problems). Conclusion: Cognitively, global ability best accounts for differences between the observed and presumed groups. Clinically, somatization also reflected significant differences between groups. Regardless of neurological status, children are likely to present with behavioral problems that precipitate referrals for neuropsychological evaluation, a finding that supports the presumption of some neurological difference.