The first four articles focus on rates of delinquency and juvenile drug use in the general population, the degree of causal independence between marijuana use and other delinquent behavior, the relationships between crack use and dealing and other delinquent behavior, and factors that place some youths at high risk of future delinquency or drug abuse. The next eight papers focus on adults, many with histories of involvement in the criminal justice system. The articles include findings taken from research on program efforts involving drug users on the street, at the point of arrest and during the pretrial period, during incarceration, and in treatment programs. The final paper describes Project REFORM, a program funded by the Bureau of Justice Assistance to assist States in reducing drug abuse and criminality among convicted offenders by establishing corrections-based drug treatment programs. Figures, tables, notes, and chapter reference lists