In the past 20 years, there has been growing interest in post-traumatic stress disorder (PTSD) in people with intellectual disabilities. It is now widely recognised that individuals with intellectual disabilities are more likely to be affected by traumatic experiences than those without. The authors discuss advancements in understanding trauma and PTSD in individuals with intellectual disabilities, as well as improvements in clinical assessment and treatment. They also emphasise the need for further research into the effects of trauma and PTSD on this vulnerable and often marginalised population.