In 1991, the Federal Bureau of Investigation reported an estimated 1.01 million State and local arrests for drug law violations. Arrests related to alcohol and other drug use increased by 126 percent during the past decade. Drug offenders accounted for 56 percent of the population in Federal correctional facilities in 1991, up from 25 percent in 1979. More than half of the inmates in local jails reported being under the influence of drugs or alcohol at the time of their offense, and over 70 percent of offenders in many metropolitan areas tested positive for drugs. The National Institute of Justice estimates that up to 80 percent of offenders, parolees, and probationers have some type of substance abuse problem related to their criminal activity. Drug-abusing offenders commit four to eight times more crimes than other criminals, and studies indicate that offenders who receive correctional or community-based drug treatment are less likely to return to criminal activity. Nonetheless, drug treatment in Federal prisons reaches only a small fraction of inmates with serious substance abuse problems. Fewer than 20 percent of State inmates with substance abuse problems receive any type of drug treatment. State correctional officials report that the lack of information about what other States are doing hinders their ability to enhance existing treatment services. State correctional officials also report limited treatment funds and difficulties in assuring adequate aftercare. Costs and benefits of providing treatment to drug offenders are considered, as well as treatment issues, options, and principles.