Experiencing aggressive behaviour has been associated with increased stress and turnover among staff who support adults with intellectual disabilities. Incident perception is a strong predictor of psychological outcomes after trauma but has not been studied in this staff group. This study clustered exposure to aggression and endorsement of emotional difficulties among 386 community residential group home staff and evaluated the contribution of four behavioural topographies to staff-rated perceived severity. Staff exposure varied considerably. Perceived severity correlated with subjective emotional difficulties. High perceived severity was associated with daily exposure, aggression towards others causing injury, and property aggression causing injury or damage. Therefore, the role the staff plays, whether a witness or target, may impact their experience.