Antisocial personality disorder (ASPD) is characterized by irresponsibility, aggression, criminality, and, in some, a lack of conscience. Recognized for over 200 years, ASPD is associated with domestic violence, psychiatric comorbidity, substance abuse, and excess health care use. ASPD is highly prevalent, and most affected individuals are men. ASPD has its onset in childhood or adolescence, when it may be diagnosed as a disruptive behavior disorder or conduct disorder. Not diagnosed until age 18, ASPD peaks in severity in the late teens or early 20s. It is lifelong for most persons, although the trend is toward improvement in those individuals with an adolescent onset and a prominent antisocial lifestyle. Those who do best have milder syndromes, are married/partnered, have stable jobs, and are older. ASPD is thought to result from a combination of genetic and environmental factors. Some antisocial persons have shown functional abnormalities in limbic structures and the frontotemporal cortex, portions of the brain that control judgment and regulate impulses. There are no effective pharmacologic treatments, but some antisocial persons receive off-label medication to dampen aggressive tendencies and curb impulsivity. Psychotropic medication is also used to treat comorbid syndromes (e.g., major depression). Cognitive-behavioral therapy may be helpful in mild cases. Family and couples therapies may be important for antisocial persons who are partnered or have offspring. This review contains 1 figure, 2 tables, and 99 references. Key words: aggression, antisocial personality disorder, conduct disorder, impulsivity, juvenile delinquency, lack of remorse, psychopathy, sociopathy