The purpose of this study was twofold: to determine the construct validities of comparable AD/HD instruments that were developed according to our current, DSM-IV classification system for AD/HD; and to identify potential +neurocognitive and socioemotional markers for AD/HD. The sample consisted of 145 children ages 8 to 11 years of age who were diagnosed with Attention Deficit Hyperactivity Disorder (AD/HD), or Central Auditory Processing Disorder (CAPD). Children were administered a battery of neurocognitive tests and completed a self-report measure of personality. Parents completed several, AD/HD instruments pertaining to their children. The AD/HD instruments used in this study were the Attention Deficit Disorder Evaluation Scale-Home Version (ADDES), Attention Deficit Hyperactivity Disorder Test (ADHDT), and the Attention Problems and Hyperactivity scales from the BASC-Monitor (BASC-M). Of interest was how each AD/HD instrument compared to the DSM-IV, particularly in terms of the cross-consistency of AD/HD subtype classifications. The findings showed that the AD/HD instruments classified participants differently from the initial, DSM-IV entry diagnosis. Rates of agreement were better for some of the AD/HD instruments than for others yet there was little overall consistency. The neurocognitive measures used in the study were the Cognitive Assessment System-Basic Battery scales. The socioemotional measures used in the study were two parent-report scales from the BASC-M (Internalizing Problems and Adaptive Skills), and the child report scales from the BASC-Self Report of Personality. Results showed that the neurocognitive measures were relatively insensitive to AD/HD symptomatology while a nearly opposite trend was observed on the socioemotional measures. For the most part, participants classified as the ADHD-Combined Type (ADHD-CT), (regardless of which AD/HD instrument was used) had the most significant impairment in areas of social functioning and emotional symptoms across parent and self-reports.