Abstract Background Qualitative research is recommended in concept elicitation for patient-reported outcome measures to ensure item content validity, and those developing measures are encouraged to report qualitative methods in detail. However, in measure development for children and young people, direct research can be challenging due to problems with engagement and communication. Objectives The aim of this systematic review was to (i) explore the qualitative and adapted data collection techniques that research teams have used with children and young people to generate items in existing measures and (ii) assess the quality of qualitative reporting. Methods Three electronic databases were searched with forward citation and reference list searching of key papers. Papers included in the review were empirical studies documenting qualitative concept elicitation with children and young people. Data on qualitative methods were extracted, and all studies were checked against a qualitative reporting checklist. Results A total of 37 studies were included. The quality of reporting of qualitative approaches for item generation was low, with information missing on sampling, data analysis and the research team, all of which are key to facilitating judgements around measure content validity. Few papers reported adapting methods to be more suitable for children and young people, potentially missing opportunities to more meaningfully engage children in concept elicitation work. Conclusions Research teams should ensure that they are documenting detailed and transparent processes for concept elicitation. Guidelines are currently lacking in the development and reporting of item generation for children, with this being an important area for future research.