Background: Care staff play a key role in identifying individuals with intellectual disabilities and additional mental health problems. Yet, few receive training in mental health, and evidence about the effectiveness of training is scant. Materials and Methods: A pre-post study is reported, using a mental health screen and a self-report questionnaire to examine staff awareness of mental health problems and to measure whether training improved knowledge of psychopathology, attitudes towards mental health services and referral decisions. Results: Prior to training, deficits in awareness were evident. The Psychiatric Assessment Schedule for Adults with a Developmental Disability (PAS-ADD) Checklist detected significant psychopathology in approximately one-third of the individuals judged to have no mental health problems according to staff. Four months after the delivery of training, significant improvements in knowledge, attitudes and referral decisions were observed. Conclusion: Brief training interventions may improve awareness of mental health problems, but further research is needed to understand the referral process and to demonstrate the role of training in influencing actual staff behaviour.