Throughout much of the last century, people addicted to drugs were thought to be morally flawed and lacking in willpower. Society's responses to drug abuse were to treat it as a moral failing rather than a health problem, which led to an emphasis on punitive rather than preventative actions. Today, we know that drug addiction is a disease that affects both brain and behavior. We have identified many of the biological and environmental factors and are beginning to search for the genetic variations that contribute to the development of the disease. This report provides scientific info. about the disease of drug addiction, incl. the many harmful consequences of drug abuse and the basic approaches that have been developed to prevent and treat the disease. Illus.