An effective system of inmate discipline is an important aspect of a safely run prison or jail. Historically, mentally ill inmates have had few or no protections against discipline routinely applied to their non-mentally ill peers. Arising from recent class action lawsuits challenging the quality of mental health care delivery in the nation's prisons, prison mental health professionals have been called on to play an increasing role in the inmate disciplinary process. Referral questions include whether an inmate is competent to proceed with disciplinary proceedings and whether mental illness may have contributed to the rule violation. Prison mental health professionals participating in inmate disciplinary proceedings must therefore be familiar with relevant clinical, legal, and ethics issues. Little has been written in the psychiatric literature, however, examining this important role for prison mental health professionals. After first reviewing core legal and constitutional concepts, the author presents the results of a nationwide survey examining the role for mental health professionals in the inmate disciplinary process. To the author's knowledge, this is the first study to provide a comprehensive review of this subject.