Supervision work in a prison Therapeutic Community is used to explore countertransference implications for staff engaging with residents' disturbed states of mind. Parallel process (a psychoanalytic concept supported by contemporary neurological findings and particularly relevant to supervisory relationships) is used to explore vulnerabilities within the staff group towards acting out the dynamics they are working with therapeutically such as attacks on linking, feelings of helplessness and cynicism, and the denial of aggression. Conversely, the development and reinforcement of the staff group's capacity to generate and preserve a thinking space while under threat has a therapeutic effect upon residents' states of mind, again through the workings of parallel process. The establishment of this benign parallel process is a central task of the Therapeutic Community, and underpins its effectiveness. Its relevance for effective therapy with disturbed states of minds in other settings is also considered.