Background: Intrusive reactive strategies (physical restraint, emergency medication and seclusion) are frequently used procedures in the management of challenging behaviour. The present study identifies predictors for reactive strategy use in an attempt to more clearly delineate at risk service users. Method: Eight hundred and thirty-nine agencies and service settings in a large area of South Wales were screened to identify children and adults with challenging behaviour against a number of defined operational criteria. Full data were available for 901 participants. Univariate and multivariate statistics were employed to identify predictors for reactive strategy use. Results: The individuals most at risk of the use of reactive strategies were those who were subject to formal detention under the Mental Health Act (restraint and sedation), had more severe challenging behaviour (seclusion), showed destructive behaviour (restraint and seclusion) were placed out of area (seclusion) and had behavioural plans in place for specific topographies (restraint and sedation). Conclusions: Individual differences such as challenging behaviour and service practices, such as detention under the Mental Health Act, predicted the use of restrictive procedures. The identification of those service users most at risk of reactive strategy use may enable the specific targeting of therapeutic interventions that may reduce or eliminate their use.