This document is intended to assist community-based behavioral health providers in their clinical and case management practice with people with mental and substance use disorders who are currently involved with or have a history of involvement in the adult criminal justice system. The focus of this document is on services provided in the community rather than in institutional settings (i.e., jail, prison, or hospital). The information provided is intended to be used in practice, and is therefore appropriate for any staff providing direct services in community settings. However, to practice these principles, organizations may need to reconsider staff training, evidence-based practices, and other programmatic elements to ensure that staff providing direct services have the information, policy support, and resources needed. This document is also intended for agency leaders and program developers who are responsible for shaping how their organizations deliver community-based services. The Principles provide a foundation for realizing a quality, community-based behavioral health treatment system that is responsive to all individuals with mental and substance use disorders and skilled in serving those with histories of justice involvement.