--- - |2+ Background Current policy in the England suggests that people with intellectual disabilities should, where possible, access mainstream mental health services; this should include access to mainstream therapy services. It is likely that mainstream therapists will need training and support to work with people with intellectual disabilities. Method Sixty‐eight therapists working in an English Improving Access to Psychological Therapies (IAPT) service received one‐ or 2‐day training on working with people with intellectual disabilities. Measures of confidence, general therapeutic self‐efficacy and attitudes to people with intellectual disabilities’ use of mainstream mental health services were completed pre‐training, post‐training and at 3‐month follow‐up; at which time, 12 participants were interviewed about the impact of the training on their practice. Results There was a significant positive change in all measures immediately post‐training which was maintained at 3‐month follow‐up. Conclusions Training considerations for mainstream therapists who may work with people with intellectual disabilities are discussed. - Journal of Applied Research in Intellectual Disabilities, Volume 31, Issue 5, Page 760-767, September 2018.