Moral injury (MI) is a potential clinical problem characterized by functionally impairing moral emotions, beliefs, and behaviors as well as adverse beliefs about personal or collective humanity and life's meaning and purpose. MI can arise from personal transgressive acts or from being a victim of or bearing witness to others’ inhumanity. Despite widespread interest in MI, until recently, there was no reliable measure of MI as an outcome, and prior research has revealed little about its causes, consequences, and intervention approaches.