Providing care and support to persons with intellectual disabilities (ID) requires in-depth knowledge about ID and challenging behaviour (CB) as well as communication and interaction. Knowledge deficiencies in these areas may prevent staff from understanding their clients and their behaviours, particularly those behaviours considered to be challenging. The aim of this study was to explore staff’s perceptions about CB among clients with ID in residential settings before and after a web-based training programme using the survey instrument ‘Checklist of Challenging Behaviour’ (CCB). The CRe-DEPTH guideline has served as a guide in this study. Upon completion of the training, staff perceived a reduced frequency of CB as well as reduced management difficulty of CB among clients. As such, training should routinely be offered to all staff in residential settings, but also healthcare professionals in general responsible for caring for clients exhibiting CB to ensure, improve and reinforce the quality of care and support provided to them.