The symptoms of attention deficit hyperactivity disorder (ADHD) often significantly impact the overall functioning of children and adolescents with this mental health condition. This chapter provides an overview of ADHD as it pertains to criteria from both the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and the Individuals with Disabilities Education Improvement Act (IDEA) category of Other Health Impairment. Cultural issues related to etiology, identification, and treatment are highlighted. The chapter addresses social, emotional, and behavioral issues that manifest in the school and home for individuals with ADHD. Implications for school psychologists and their role in assessment, advocacy, consultation, and therapeutic intervention are discussed.