If positive behavioural support is to recoginse the presence of trauma whether in association with intellectual disability or in those providing services, an understanding of the core concepts and associated diagnostic frameworks is required. This paper therefore examines contemporary thinking around post traumatic stress disorder (PTSD) and discusses the emergence of the concept of complex trauma. By means of an exploration of the impact of adverse childhood experiences, it then suggests that trauma may exert a significant impact, even where strict diagnostic criteria are not fulfilled and that a wider understanding of the impact of trauma on the lives of service users and service providers is required by practitioners. You can request a copy of this article by replying to this email. Please be clear which article you are requesting.