Culturally Grounded Positive Psychology Interventions for Nigerian Secondary School Students: Development, Validation, and Longitudinal Impact Study

This study develops, validates, and longitudinally evaluates a suite of culturally grounded positive psychology interventions for Nigerian secondary school students, making an original contribution to both positive psychology and cross-cultural educational intervention science. Positive psychology interventions including gratitude practices, strength identification, and meaning-making activities have strong evidence bases in Western contexts, but their direct transplantation to Nigerian schools risks cultural inauthenticity and reduced effectiveness. The study employs a four-phase design: cultural grounding through community-based participatory research involving 120 students, teachers, and parents across South West, South South, and North Central Nigeria; intervention adaptation and expert validation using consensus techniques; randomised controlled trial across 18 secondary schools involving 540 students with follow-up at 6, 12, and 18 months; and economic analysis. Outcome measures include subjective well-being, academic engagement, character strengths, and academic achievement. Culturally adapted elements include Ubuntu-informed collective gratitude practices, Yoruba owe proverbs in strength reflection activities, and community contribution framing of purpose exercises. Data were analysed using multilevel modelling, latent growth curve analysis, and cost-effectiveness calculations. Results demonstrate significantly greater and more sustained positive well-being and academic engagement gains for the culturally grounded intervention compared to a Western-adapted condition and an active control. The 18-month follow-up shows continued divergence, suggesting that cultural authenticity contributes to long-term intervention durability. Keywords: positive psychology, cultural adaptation, intervention development, secondary school, Nigeria.