Objective: We extended the Cognitive and Academic Intra-Individual Variability (IIV) research by comparing three computational models, Overall Test Battery Mean Standard Deviation (OTBMSD), CV (Coefficient of Variance), and Range as markers of Attention-Deficit Hyperactivity Disorder (ADHD) and Learning Disorder (LD). Method: Archival data (N = 505) consisted of three groups: control (n = 148), LD (n = 173), and ADHD (n = 184). Most were Caucasian (n = 434), half were males (n = 255), and mean age was 22.5 years (SD = 6.1). OTBMSD was calculated using each individual's cognitive & academic performance based on the standard scores of the Wechsler Adult Intelligence Scale-III (WAIS-III) and Woodcock Johnson-III (WJ-III). Each OTBM was divided by the OTBMSD to calculate CV, cognitive and academic Ranges. Analyses were conducted using correlations, Kruskal-Wallis, LSD, and Games-Howell. Results: OTBMSD analyses yielded significant differences for cognitive performance between all groups (p = .000) and subtypes of LD and ADHD (p = .012 to.032). CV significantly differentiated cognitive performances between LD and ADHD (p = .011), and between LD and ADHD subtypes (p = .003 to .032). Range analyses and WJ-III IIV exhibited no significant differences between groups, though Broad Reading & Broad Math IIV were more closely related (r = .27) than Broad Writing IIV (r = .038 & .054), which was significantly related to Cognitive IIV (r = .097). Conclusion(s): Findings suggest Cognitive IIV calculated as WAISIII OTBMSD & WAIS-III CV detects specific cognitive pathologies, but Range and Academic IIV are not discrepant markers of pathology. Except for Broad Writing IIV, Academic IIV and Cognitive IIV are unrelated.