Such programs have existed since the 1960's, but they were cut back sharply in the 1980's. The BOP statement noted that at least 40 percent of the inmate population has a substance abuse problem. The new standards require all new inmates to undergo a substance abuse assessment during their initial psychological screening. BOP also provided resources for more intensive treatment programs. Enrollment in treatment programs is currently voluntary, although many inmates are under court order for substance abuse treatment. Most programs emphasize education, but one-third of the institutions have self-help groups like Alcoholics Anonymous. A variety of other approaches are also used. A conference convened by BOP in September 1988 focused on current research findings and operational considerations. It recommended treatment beginning early in incarceration, the use of a multifaceted continuum of care, and provision of long-term treatment. Following the conference BOP staff began to develop a plan for future drug-treatment programming using a therapeutic community structure and including an evaluation methodology.