ADHD is currently understood to be a disorder of inattention, impulsivity, and usually hyperactivity that arises in childhood or early adolescence and is highly persistent over time in most cases. However, since the first medical papers have been published on ADHD starting in 1798, emotion has always been included in the conceptualization of the disorder up through the 1970s. But beginning with DSM-II and progressing to the present, emotional dysregulation has been excluded from the clinical conceptualization of the disorder and the diagnostic criteria and relegated to an associated problem or the result of comorbid disorders. This presentation reviews the evidence from the history, neuropsychology, neuro-anatomy, and observational research that shows that emotional impulsiveness and deficient emotional self-regulation are an integral part of ADHD. Returning emotion to its rightful place as a core feature of the disorder also serves to better explain the development of comorbid disorders, such as oppositional defiant disorder, and well as various life course impairments. Dr. Barkley discusses how to determine which aspects of emotional adjustment problems in ADHD cases are the result of the disorder and which are likely to be the consequence of comorbidity or other life course circumstances. He also addresses the implications of including emotion in ADHD for its management.