Background: There is frequently great concern about the dangerousness of deinstitutionalized men with intellectual disabilities who have been institutionalized because they are considered to be at high risk for the commission of serious antisocial acts or sexual offending. Unfortunately, there is little information on whether changes in the behaviour of these men can be used to adjust supervision so as to manage risk. Methods: An appraisal of men with intellectual disabilities and histories of serious antisocial behaviours who were residing in institutions about to be closed led to a 16 month follow-up of 58 of these clients who had been transferred to community settings. Results: A total of 67% exhibited antisocial behaviour of some kind and 47% exhibited "hands-on" violent or sexual misbehaviours directed toward other clients or staff. The Violent Risk Appraisal Guide was the best predictor of new violent or sexual incidents and a variety of other pre-release predictors were related to the likelihood of antisocial incidents of any kind. Overall predictive accuracy was moderate. A field trial showed that monthly staff ratings of client characteristics were related to antisocial incidents. Conclusions: These preliminary data indicate that measures of dynamic risk involving staff ratings are worth developing and evaluating.