Reasons why people might behave in ways that are challenging for others include dementia and learning disabilities. The ways in which caregivers, who may be family members or staff, make sense of the causes of these behaviours can affect how they respond to the person. Additionally, challenging behaviours can have an emotional impact on caregivers, which may affect the attributions they make about the behaviours. A systematic literature review was conducted to identify factors which are related to the causal attributions carers make about challenging behaviours. Sixteen quantitative studies that had examined carer attributions in the areas of learning disabilities and dementia care were reviewed. A wide range of factors had been examined in relation to attributions, which were grouped for comparison into: carer and individual demographics, individual’s level of impairment and type/ severity of behaviour, service and environmental factors and carer emotions. Some factors were identified as being associated with carer attributions, including the level of impairment of the individual and the type of challenging behaviour. A qualitative research project was conducted: nine direct care staff in a residential dementia care setting took part in individual semi-structured interviews about their emotional experiences of working with challenging behaviours. Interpretative phenomenological analysis was used to analyse the data, and three broad themes were constructed: “They don’t know what they’re doing”: Understanding causal attributions; “It’s knowing them as people”: Getting to know people with dementia; and “That’s part of the job”: Experiences of the role of care staff. These themes were discussed with reference to the literature, and clinical implications and directions for future research were proposed.