Methamphetamine has risen to the top of the American drug-policy agenda. For most of its history, it was regarded in law and public opinion as a secondary or regional concern, different from and less damaging than the drugs -- heroin, cocaine, and marijuana -- that have defined the focus of national drug policy. More recently, however, as the production, trafficking, and use of methamphetamine have spread, a gathering consensus has come to regard it as one of the most dangerous substances available in illegal markets. Methamphetamine's dangers, including the devastating impact of the drug on child welfare and health care systems in blighted communities, the risk of fires and explosions and the environmental contamination resulting from illicit manufacture of the drug, and the rapid increase in foreign suppliers of the drug are likely to keep this drug problem at the forefront of the congressional agenda. Existing evidence of the pattern of methamphetamine abuse and the effectiveness of alternative responses to its abuse are in some cases highly imperfect, and policymaking in this field remains an exercise in decision making under uncertainty. There is, however, little doubt that methamphetamine use has risen significantly since the early 1990s. Indeed, this trend arguably is the most important change in drug consumption patterns since the crack cocaine epidemic of the late 1980s and early 1990s.