AIM:To evaluate the psychometric properties and performance of the 32-item Thriving of Older People Assessment Scale (TOPAS) and to explore reduction into a short-form. BACKGROUND:The 32-item TOPAS has been used in studies of place-related well-being as a positive measure in long-term care to assess nursing home resident thriving; however, item redundancy has not previously been explored. DESIGN:Cross-sectional study. METHOD:Staff members completed the 32-item TOPAS as proxy raters for a random sample of Swedish nursing home residents (N = 4,831) between November 2013 - September 2014. Reliability analysis, exploratory factor analysis and item response theory-based analysis were undertaken. Items were systematically identified for reduction using statistical and theoretical analysis. Correlation testing, means comparison and model fit evaluation confirmed scale equivalence. RESULTS:Psychometric properties of the 32-item TOPAS were satisfactory and several items were identified for scale reduction. The proposed short-form TOPAS exhibited a high level of internal consistency (α = 0.90) and strong correlation (r = 0.98) to the original scale, while also retaining diversity among items in terms of factor structure and item difficulties. CONCLUSION:The 32-item and short-form TOPAS' indicated sound validity and reliability to measure resident thriving in the nursing home context. IMPACT:There is a lack of positive life-world measures for use in nursing homes. The short-form TOPAS indicated sound validity and reliability to measure resident thriving, providing a feasible measure with enhanced functionality for use in aged care research, assessments and care planning for health-promoting purposes in nursing homes.