Objectives To validate PedsQLTM for children in public care and develop an ‘in‐care’ module. Design and setting Questionnaire development and validation. Questionnaires were completed in placement. A total of 69 children in public care (aged 8–18 years) and their carers were recruited through routine paediatric assessments, and 662 children not in public care were recruited from local schools. Measures Self‐ and proxy‐report versions of PedsQLTM generic module and the ‘in‐care’ module. Results Cronbach's alpha for the generic module ranged from 0.66 to 0.88 and from 0.74 to 0.90 for self‐ and proxy‐report respectively. Lower scores were reported for children in care compared with peers living at home for proxy‐ and self‐report. Proxy‐ and self‐report correlation ranged from 0.43 to 0.60 (P < 0.001). Cronbach's alpha for the in‐care module was 0.87 and 0.91 for self‐ and proxy‐report respectively. Proxy‐ and self‐report scores showed significant correlation with generic module scores. The highest correlations were seen with sub‐scales measuring Psychosocial Functioning (e.g. Emotional Functioning: Pearson's r = 0.67 and 0.59, P < 0.001 for self‐ and proxy‐report respectively). Proxy‐ and self‐report correlation was 0.45 (P < 0.001). Conclusions We found PedsQLTM generic module and the newly developed ‘in‐care’ module to have excellent internal reliability for self‐ and proxy‐report. Validity was established for both measures and significant correlation found between child and proxy ratings. Although further testing of the measures is recommended, both have potential value in assessing the success of placements and could provide a reliable and valid tool for individual patient analysis in clinical practice and for research with this group.