Any lifetime history of injection drug use (IDU) is associated with markedly elevated rates of addiction to alcohol and other substances on a lifetime basis. In this population, substance use tends to manifest early in life, as do conduct problems such as school disciplinary problems, theft, fighting, and juvenile arrest. Many people who inject drugs will ultimately merit a diagnosis of antisocial personality disorder. Rates of depressive illness and anxiety disorders are also high in this population, and IDU is associated with high rates of suicidal ideation, suicide attempt, and completed suicide. The severity of social, medical, and psychiatric disability in this population poses significant treatment challenges. [ Psychiatr Ann . 2017;47(1):27–32.]