This paper focuses on the development of Keep Safe, a manualised group intervention for adolescents with intellectual disabilities who display harmful sexual behaviour (HSB), and is the initial phase of a feasibility study. National reports have highlighted the need for the development of specialist programmes, as adolescents with intellectual disabilities make up a significant proportion of young people referred to specialist HSB services and there is a lack of evidence or practice-based interventions for them. Keep Safe development concurrent parental/ carer sessions (some joint). The main focus of Keep Safe is to enhance well-being and reduce harm. Four initial sites volunteered as feasibility leads, and 2 more were added as recruitment was more difficult than foreseen. This study is innovative and valuable given the recognition that research and practice is significantly lacking in this area.