The present research addressed gaps in our current understanding of validity and quality of measurement provided by patient reported experience measures. We established the psychometric properties of a freely available experience of service questionnaire (ESQ), based on responses from 7,067 families of patients across 41 UK providers of child and adolescent mental health services, using the two-level latent trait modeling. Responses to the ESQ were subject to strong 'halo' effects, which were thought to represent the overall positive or negative affect towards one's treatment. Two strongly related constructs measured by the ESQ were interpreted as specific aspects of global satisfaction, namely satisfaction with care, and with environment. The Care construct was sensitive to differences between less satisfied patients, facilitating individual and service-level problem evaluation. The effects of nesting within service providers were strong, with parental reports being the most reliable source of data for the between-provider comparisons. We provide a scoring protocol for converting the hand-scored ESQ to the model-based population-referenced scores with supplied standard errors, which can be used for benchmarking services as well as individual evaluations.