Chapter 9 reviews background information concerning attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and Tourette’s disorder (TD). Prevalence, comorbidity, and multicultural findings are presented for each disorder. Information pertaining to the role of genetics is reviewed, including family, twin, and candidate gene studies. Structural brain imaging findings are critically evaluated along with findings from functional neuroimaging studies. Pharmacological interventions are reviewed for all three disorders and information is presented regarding the safety of these medications. Lastly, information pertaining to alternative interventions, as well as neurosurgery and brain stimulation, is reviewed.