The Illinois plan is based on four principles: (1) alcohol and other drug abuse are factors in most crimes; (2) drug treatment decreases criminality; (3) drug treatment is effective in the prison setting; and (4) drug treatment effectiveness is enhanced when combined with strong post-release treatment, case management, and monitoring. Plan goals are to reduce drug abuse, rehabilitate criminal offenders and enable them to become productive citizens, and to deter repeat offenses through treatment in prisons and communities. The plan focuses on intervention from the time of incarceration through reintegration into the community. This continuum includes a regional system of access to self-help groups, drug education, drug counseling, intensive treatment levels with transitional programming for individuals under the Department of Corrections, and case management and community-based treatment after release from correctional institutions. The importance of program evaluation to assess the plan's long-term success is emphasized, and implementation steps and associated costs are noted. 17 footnotes, 3 tables, and 2 figures