Adaptation and validation of the Intrinsic Motivation Inventory (IMI) in Polish

Introduction: The aim of this study was to adapt the full 45-item, seven-subscale Intrinsic Motivation Inventory (IMI) into Polish and evaluate its psychometric properties, including cross-language measurement invariance in Polish-English bilinguals. Methods: ), cross-language correlations, and confirmatory factor analyses (CFA; WLSMV/THETA) were conducted, while language invariance was tested using a CT-C(M-1) framework comparing marker-configural and strict metric models. Convergent and divergent validity were assessed through associations with external constructs related to motivation, control, curiosity, and stress appraisal. Results: CFA supported the expected seven-factor structure in both languages with good model fit, and language invariance analysis indicated minimal configural-metric differences, suggesting approximate measurement invariance. The Polish IMI demonstrated strong internal consistency across all subscales, closely matching the English version, while cross-language correlations confirmed strong subscale-level equivalence, though a small number of items showed weaker psychometric properties. Subscale intercorrelations followed theoretical expectations, supporting construct validity, with subscales reflecting engagement, autonomy, and competence aligning most strongly with positive motivational constructs. Overall, the Polish IMI is suitable for research in Polish, with all materials, data, and analysis code openly available.