Background: In this study, we explored the extent to which the knowledge and attributions of support staff predicted their reported helping behaviour in relation to people with an intellectual disability who displayed challenging behaviour (CB), and whether emotion regulation style moderated the relationship between attributions and this helping behaviour. Method: Participants (N = 107) completed self-report measures of knowledge of the meaning and management of CB, causal attributions and behavioural response to CB, and emotion regulation style. Results: Knowledge and helpful attributions were significantly correlated with reported helping behaviour; however, in a regression analysis with both predictors, only knowledge significantly contributed to the variance. No moderating effect was found for emotion regulation styles on the relationship between attributions and reported helping behaviour. Conclusion: Knowledge was the only significant predictor of reported positive staff approaches in managing CB, giving some support for the provision of staff training aimed at increasing knowledge, rather than changing attributions.