Attention-deficit/hyperactivity disorder (ADHD) is one of the most common childhood-onset neurobehavioral, psychiatric disorders, affecting from 3% to 8% of children in the United States. For 60% to 85% of affected children, ADHD persists into adulthood. The disorder is characterized by symptoms of inattention and/or hyperactivity with impulsivity that manifest as poor concentration, overall disorganization, and fidgeting, which can negatively impact an individual's ability to function in more than one domain (e.g., school, home, work), and can impair self-esteem and interpersonal relationships. Diagnostic criteria from the text revision of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition® (DSM-IV-TR) help clinicians establish a diagnosis of ADHD. Current standards of practice recommend an integrated approach for the diagnosis of ADHD, incorporating clinical data from self-reports, clinical interviews, comprehensive physical examination, behavior and symptom checklists, standardized behavior rating scales, and psychometric testing. Diagnosis is often complicated by the reliance on interviews and evaluations since they may provide highly subjective or conflicting information regarding behavior and symptoms of ADHD and comorbidities. Consequently, there is growing interest in the development of objective laboratory measures that enhance the overall diagnostic approach to ADHD. Neuropsychological tests, such as the Quotient ADHD system (BioBehavioral Diagnostics Company [BioBDx]), objectively measure impulse control, the ability to sustain attention, and movement. These tests are being evaluated for their clinical utility as predictors of ADHD, and some have been marketed for clinical use as objective measures of ADHD-associated impairment.