To assess the impact of a multi-tiered oral health education programme on care staff caring for people with intellectual disability (ID). Postal questionnaires were sent to all care staff of a community-based residential care service for adults, randomly assigned to control and intervention groups. A specifically developed training programme was delivered to residential staff nominees, who then trained all staff within the intervention group. The control group received no training. Post-test questionnaires were sent to both groups. Paired-samples t-test was used to compare oral health-related knowledge (K) and behaviour, attitude and self-efficacy (BAS) scores. Of the initial 219 respondents, 154 (response rate between 40% and 35.8%, with attrition rate of 29.7% from baseline to repeat) returned completed questionnaires at post-test (M=8.5 months, range=6.5-11 months). Control and intervention groups were comparable for general training, employment and demographic variables. In the intervention group, mean Knowledge Index score rose from K=7.2 to K=7.9 (P<0.001) and mean BAS scale score rose from BAS=4.7 to BAS=5.4 (P<0.001). There was no statistically significant increase in mean scores from test (K=7.0, BAS=4.7) to post-test (K=7.2, BAS=4.9) for the control group. Mean scores regarding knowledge, attitude, self-efficacy and reported behaviour increased significantly at 8.5 months in staff where training was provided. The results indicate that a multi-tiered training programme improved knowledge, attitude, self-efficacy and reported behaviour amongst staff caring for people with ID.