This issue of the Child and Adolescent Psychiatric Clinics will be Part I of II on Substance Use Disorders. Part I will be edited by Drs. Ray Hsiao and Leslie Walker. They present an overview of prevalence and patterns, the neurobiology of adolescent abuse, and evidence-based prevention. This volume will cover a wide array of substances including, alcohol, cannabis, tobacco, stimulant, opioid, hallucinogens, inhalants, and even internet addiction or abuse, among other topics.