The experts selected for the workshop were prison, jail, probation, and parole administrators, as well as researchers and mental health care professionals, who discussed aspects of managing seriously mentally ill (SMI) offenders in the justice system across six subject areas. This article does not include a discussion of all 47 identified needs, but the critical takeaways from the expert workshop included the prioritization of the needs of the seriously mentally ill; the need for early detention and intervention for children at risk for or exhibiting mental illness; the improvement of community-based mental health services; a focus on treatment rather than prevention; and barriers to collaboration between the justice system and the mental health system that continue to disrupt care for the mentally ill. As public resources become more scarce, the SMI population will continue to grow. Those individuals’ engagement with the criminal justice system will likely increase as well. That reality requires focused dialogues to drive research priorities and commitments related to SMI needs in corrections. Individuals with serious mental illness, the institutions tasked with managing them, and society itself will pay a steep price if SMI challenges are unmet.