Development and validation of the youth development instrument (YDI): A comprehensive survey of adolescent health and well-being

• Comprehensive Adolescent Well-Being Survey : The Youth Development Instrument (YDI) is a school-administered, self-report survey designed to assess individual and contextual protective and promotive factors influencing adolescent health and well-being. • Strong Psychometric Properties : Factor analyses demonstrated that YDI measures exhibit unidimensionality, good internal consistency (mean Cronbach’s α = 0.85), and expected construct validity correlations with thriving, resilience, and prosocial orientation. • Strengths-Based and Developmental Approach : The YDI employs a strengths- and assets-based framework, drawing from Bronfenbrenner’s bioecological theory and developmental psychopathology to assess adolescent well-being holistically. • Student Engagement : As part of our commitment to participatory action research, the YDI Youth Advisory Council was created prior to survey development and were instrumental in guiding, testing and interpreting the work. • Large-Scale Validation in Schools : The YDI was piloted among 2,295 eleventh-grade students across 31 schools in British Columbia, Canada, revealing robust measurement properties for monitoring youth development. • Implications for Policy and Practice : The YDI provides a valuable tool for informing school- and community-based interventions, supporting youth well-being trajectories, and linking with population-level education and health data. Strengths-based approaches are urgently needed to protect and promote adolescent well-being in the United States and Canada, where adolescent happiness and mental health rank among the lowest of the world’s wealthiest countries. Identifying protective and promotive factors for adolescent well-being is critical for guiding policy, public health, and education sector responses as adolescents face unprecedented challenges. We examined the dimensionality and psychometric properties of the Youth Development Instrument (YDI), a comprehensive survey of adolescent health and well-being within a longitudinal well-being monitoring system. The YDI draws predominantly from existing, validated measures identified as fundamental to adolescent well-being. We describe the survey creation process in consultation with adolescents, interdisciplinary experts, and partners in adolescent development, medicine, policy, psychology, psychiatry, education, and public health. We conducted psychometric analysis of the YDI pilot implementation among 2295 eleventh-grade students across 31 schools in British Columbia, Canada, in 2021. We examined each measure’s dimensionality and relationship with thriving, resilience, and prosocial orientation to assess their construct validity. Exploratory and confirmatory factor analyses demonstrated the uni-dimensionality of each measure. Most measures had good or excellent internal consistency (mean Cronbach’s α: 0.85) and demonstrated moderate or large magnitude correlations to thriving, resilience, and/or prosocial orientation and small correlations with family affluence as hypothesized. Correlation patterns aligned with theoretical literature. The YDI is a comprehensive and psychometrically sound survey of adolescents’ well-being and protective and promotive factors. The YDI’s linkable nature also creates potential for measuring population-level mental health and wellbeing trajectories. Development and Validation of the Youth Development Instrument (YDI): A Comprehensive Survey of Adolescent Health and Well-Being.