Background: Narrative exposure therapy (NET) is a trauma-focused cognitive behavioural therapy, recommended by the National Institute for Health and Care Excellence in 2018, to treat posttraumatic stress disorder in adults. There is a lack of research exploring the effectiveness of NET with adults with intellectual disabilities. The aim of this study is to develop an adapted version of the NET protocol (IDNET) for use with adults with mild intellectual disability. Methods: A qualitative research design was employed. Stage one involved systematically adapting the NET protocol for adults with mild intellectual disabilities in collaboration with a service user group comprising eight consultants. Stage two involved gaining professionals' views on the adapted protocol and on the use of NET in intellectual disability services. This comprised a focus group of eight clinical psychologists specialising in intellectual disabilities and an expert panel of three NET clinicians. The framework approach was conducted on the focus group data only following guidance from a previous study. Findings: An adapted NET protocol and collection of 'easy read' therapy materials were developed (IDNET), which incorporated feedback from the three stakeholder groups. Key concepts of 'Optimism and motivation to adapt NET for people with mild intellectual disabilities' and 'Factors related to NET in practice' were developed to describe the views of clinical psychologists. A number of issues were raised by professionals regarding the delivery of IDNET. Conclusions: Professionals were optimistic about IDNET; however, issues raised regarding the delivery of IDNET require exploration when IDNET is trialled in practice. Specific implications for clinical practice and future research are discussed.