Current behavioural models incorporate challenging behaviour and staff actions into a 'dynamic behavioural system'. Central to this model is the hypothesis that challenging behaviour is aversive to others, and consequently that staff engage in escape behaviour, which serves to maintain challenging behaviour. This thesis seeks to increase our current knowledge of the application of cognitive models to understand the emotional and cognitive responses of staff to challenging behaviour. The first paper, a literature review, discusses both the findings of existing research on staff attributions, emotional reactions and behavioural responses to challenging behaviour, and research that examine whether Weiner's attributional model of helping behaviour can help to explain staff responses. The second paper seeks to conduct a more theoretically appropriate test of Weiner's helping model, and to improve methodologically on previous studies. The paper aims to establish, using an experimental design, that emotional reactions will mediate the impact of causal attributions on interventions ('helping' behaviour). Participants were presented with one of two video stimuli, which depicted self-injurious behaviour that was either positively reinforced or negatively reinforced. The results indicate that emotional reactions do not play a mediating role in the helping behaviour of staff, and therefore that there is no evidence for the application of Weiner's helping model. Implications for research and clinical practice are discussed.