Sixteen percent of people in jail are mentally ill, compared to only 5 percent of the general population. Upon release, the criminal justice system does not provide effective post-custody care. Mentally ill offenders have difficulty independently complying with supervision terms, accessing treatment, and addressing areas of their lives that are disrupted by incarceration. The excessive caseloads of probation and parole hinder the ability to provide the close supervision and linkage of treatment that many mentally ill offenders require. Punitive re-incarceration may be an unnecessarily harsh and ineffective sanction for substance-using individuals that are trying to abstain from drug use. Effective community treatment is the key to breaking this cycle and helping mentally ill offenders achieve stability in the community without re-incarceration. San Francisco’s District Attorney has been a vocal supporter of incorporating harm reduction into a criminal justice setting. Harm reduction is an increasingly accepted philosophy, based on public health principles, that is intended to reduce the harm of drug use to both the user and to society. Harm reduction views a reduction in drug use or a change to a safer kind or method of drug use as a success. Harm reduction has been shown to be one of the few successful drug treatments for this difficult-to-reach population. The intensive case management model, providing holistic, continuous case management, is a success story in the mental health field. But within the criminal justice system, research has shown that intensive supervision can increase recidivism. The keys to addressing this challenge are dialogue and education about treatment methods and collaboration around treatment planning between mental health and criminal justice. The harm reduction and case management models are effective at their stated purpose: protecting public safety, decreasing the continued re-incarceration of mentally ill people, and reducing jail overcrowding and criminal justice costs. References