Background A cohort of 11 patients with an intellectual disability and a psychiatric diagnosis present severe behavioural disorders in psychiatric hospital of Quebec in 2009. Control‐measure use for this clientele has now been reduced. How do management personnel, families and care teams explain the changes? What clinical interventions did management and care providers implement that contributed to the reduction? Method A retrospective case study was conducted. Five focus groups were held with people involved in their care, and the patient files were examined. Results The factors contributing to this change were the cohesion of the care providers, the involvement of the families and the efforts to determine the function of the behaviour. Implications This study may inspire other care teams to try new approaches in dealing with patients with severe behavioural disorders. Also, the model of factors and interventions supporting a reduction in seclusion and restraint measures may inspire future studies.