Life story work is a way of supporting children who spend time in out-of-home care to make sense of their experiences. It is highly valued yet poorly evidenced and inconsistently implemented with adolescents aged 12–18 years old. We sought to improve our understandings of the ways in which carers are already supporting what we describe as adolescent-focused low-intensity life story work (AF-LI-LSW) to improve the quality, consistency and availability of this support. We collected data from seventy-eight participants (adolescents, carers and social care professionals) from eight English Local Authorities. Using a participatory realist evaluation, we analysed qualitative and quantitative data to develop and test our understandings of AF-LI-LSW. We developed seven principles indicating that AF-LI-LSW is likely to be optimal when: it is flexible and person-centred; starts early; begins in the present; provides future storytelling prompts; adolescents are encouraged to participate; focusses on everyday life and when training and support is available. Participants’ experiences were characterized by several dilemmas. The need to offer (and desire for care-experienced adolescents to enact) participation choices whilst acting in the best interest of adolescents in current and possible future contexts. Our findings provide guidance for carers, adolescents and children’s out-of-home care more broadly.