Methamphetamine is an equal or greater contributor to criminality than crack cocaine. Methamphetamine (MA) is similar in chemical structure to amphetamine, but has more pronounced effects on the central nervous system. Like amphetamine, MA causes increased activity, decreased appetite, and a general sense of well-being. Chronic abuse can lead to a dose-related stimulant psychosis, characterized by intense paranoia with ideas of reference and out-of-control rage coupled with extremely violent behavior. MA dependence is a serious problem in the United States that has historically occurred in waves that resemble patterns seen in epidemics of infectious disease. In addition to the role of amphetamines in violence, alcohol sharply diminishes impulse control, and stimulants can produce paranoia and lead to pre-emptive violence. Drug use and teenage violence need to be placed in a broader context that includes education, prevention, and treatment as well as criminalization. The drugs themselves are potent contributors to violence, and increased attention needs to be paid to the role of substance abuse in violent behavior. Further, expanded treatment for addiction needs to be presented as a cost-effective crime prevention technique as well as a humane alternative to incarceration. 27 footnotes