Background: Positive Behavioural Support (PBS) has been shown to be effective in minimizing challenging behaviour and improving the lives of people with intellectual disabilities. Training in PBS is an important factor in achieving good coverage in the use of PBS. The aim of this study was to evaluate the impact of training managers of social care services in PBS. Method: A year-long training programme in PBS was delivered to 50 managers of community-based services for people with challenging behaviour. Data were collected pre- and post-training, and at six month follow-up. A non-randomized control group design was used. Results: Data demonstrated significant reduction in challenging behaviour. However, there was no change in quality of life for service users. Conclusion: Training in PBS can reduce challenging behaviour in people with intellectual disabilities; demonstrating any impact of PBS training on quality of life remains a challenge.