This study reported on research conducted in a high security psychiatric hospital in the United Kingdom managing patients considered dangerous, violent, or who had criminal propensities (tendencies). Within these hospitals violence and aggression were common occurrences with staff responding to these threats in several ways. This study aimed to: (1) establish the range and frequency of the use of seclusion as a response to threatened and actual violence; (2) examine differences between staff assessment of a patient’s seclusion in relation to the rationale for its employment; and (3) examine the relationship between the duration of seclusion in relation to the reason for its initiation. Data were collected on a random selection of 95 seclusion episodes over a 6-month period occurring in the hospital. Results indicated that there was an over-prescription of seclusion in response to actual violence. Despite the lack of mental state assessment, there was also a significantly longer duration of seclusion when staff was targeted. Tables and references