The rise in heroin use in the 1990s is attributed to an increase in snorting and smoking heroin as opposed to earlier epidemics that relied on intravenous use. An increase in purity has also added to the addiction problem. The trend towards use by young people was confirmed by the 2000 Monitoring the Future Study, which reported that 10.6% of high school seniors had tried heroin. This document discusses problems faced by the Caron Foundation in treating this new wave of heroin use. It includes profiles of addiction as well as the current trends in heroin use. There is extensive information about the biological, psychological, and social issues surrounding heroin, heroin use, its pharmacological impact, and various treatment protocols. (Contains 15 figures and 53 references.) (ADT)