The Moderating Role of School Adjustment in Character Strengths Interventions: A Field Study on Elementary School Students’ Basic Psychological Needs Satisfaction and Subjective Wellbeing

Competitive academic climates in East Asia place students at heightened psychosocial risk. Guided by the person-activity-fit models, we tested whether school adjustment moderates the efficacy of three character-strengths interventions—signature, growth, and combined—in Basic Psychological Needs Satisfaction (BPNS) and enhancing subjective wellbeing. A quasi-experimental field study was conducted with 549 fifth- and sixth-grade students from two urban Korean schools. Classrooms were assigned to a signature-strengths, growth-strengths, combined, or emotion-focused active-control condition. Each programme comprised an 80-minute workshop along with seven days of structured practice. Autonomy, competence, relatedness, and subjective wellbeing were measured pre- and post-intervention. Baseline school-adjustment scores served as a continuous moderator. Multiple-regression models and Johnson–Neyman probes tested interaction effects. No intervention outperformed the active control at the average level. However, growth-strengths × school-adjustment interactions were significant for autonomy (β = -.10, p = .040) and competence (β = -.12, p = .008). Students with low school adjustment showed greater gains in autonomy and competence than control groups. Relatedness and subjective wellbeing were not significantly affected. Strengthening under-expressed (‘growth’) strengths appears especially beneficial for students with low school adjustment. These findings support a compensatory perspective on targeted strengths development. Signature-strengths lessons may therefore be complemented with growth-oriented modules for low-adjustment learners, alongside relational supports to support relatedness.