AUTHOR=Martin-Gagnon Gabriel , Fonagy Peter , Bégin Michaël , Normandin Lina , Ensink Karin TITLE=Measuring mentalizing in youth: further validation of the reflective functioning questionnaire for youth (RFQY-13) JOURNAL=Frontiers in Psychology VOLUME=Volume 14 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2023.1260281 DOI=10.3389/fpsyg.2023.1260281 ISSN=1664-1078 ABSTRACT=Objective: This study investigated the psychometric properties, including the factor structure, validity, and reliability of the 13-item Reflective Function Questionnaire for Youth (RFQY-13), using a new scoring system.: A community sample of 414 adolescents and a clinical sample of 83 adolescents (aged 12-21) completed the RFQY, the Borderline Personality Features Scale for Children (BPFS-C), the Beck Youth Inventories (BYI), the Child Behavior Checklist-Youth Self Report (CBCL-YSR) and the Movie for the Assessment of Social Cognition (MASC).Results : Using the new scoring system, our results demonstrated configural and metric invariance, as well as adequate reliability and validity across both samples for the two-factor structure of the RFQY. The Uncertainty subscale showed strong associations with psychopathology and differentiated between clinical and community samples, with the clinical sample reporting significantly higher Uncertainty.Discussion : The findings show that the RFQY-13, when used with the new coding system, has good psychometric properties and is a reliable measure of mentalizing for adolescents and young adults. We discuss clinical implications, limitations and future directions.