1 Department of Psychology, Universidad del Norte, Puerto Colombia, Colombia. Electronic address: mmebarak@uninorte.edu.co.
2 Cyberpsychology Laboratory and Department of Psychoeducation and Psychology, Université du Québec en Outaouais, Saint-Jérôme, Canada; Substantive-Methodological Synergy Research Laboratory, Department of Psychology, Concordia University, Montreal, Canada.
3 Department of Psychology, Universidad del Norte, Puerto Colombia, Colombia; Department of Mathematics and Statistics, Universidad del Norte, Puerto Colombia, Colombia.
4 Polibienestar Research Institute, University of Valencia, Valencia, Spain; Department of Personality, Evaluation, and Psychological Treatments, University of Valencia, Valencia, Spain.
5 Polibienestar Research Institute, University of Valencia, Valencia, Spain; Department of Personality, Evaluation, and Psychological Treatments, University of Valencia, Valencia, Spain; CIBER of Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain.
6 CIBER of Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain; Department of Clinical and Health Psychology, Institute of Psychology and Education, Ulm University, Germany.
7 Department of Personality, Evaluation, and Psychological Treatments, University of Valencia, Valencia, Spain; CIBER of Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain.
8 CIBER of Physiopathology of Obesity and Nutrition (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain; Department of Clinical and Health Psychology, Institute of Psychology and Education, Ulm University, Germany; Department of Psychology and Sociology, University of Zaragoza, Teruel, Spain.
9 School of Psychology and Sport Science, Anglia Ruskin University, Cambridge, United Kingdom; Centre for Psychological Medicine, Perdana University, Kuala Lumpur, Malaysia.

The Functionality Appreciation Scale (FAS) is increasingly used in diverse national and linguistic contexts. However, limited work has assessed the extent to which the instrument demonstrates measurement invariance and differential item functioning (DIF) across nations and respondent characteristics. Here, we examined measurement invariance and DIF of the FAS using archival data from adults in Colombia (Mebarak et al., 2023) and Spain (Zamora et al., 2024). Participants included 1420 (women n = 804, men n = 616) respondents from Colombia and 838 (women n = 415, men n = 423) respondents from Spain who completed translations of the FAS. Confirmatory factor analysis supported a unidimensional structure of the FAS in both national groups. Additionally, the FAS achieved full measurement invariance (up to latent mean invariance) across both groups. We also found that the FAS lacked DIF as a function of age, body mass index (BMI), and gender identity across both national groups. Older participants (relative to younger participants), men (relative to women), and participants with lower BMIs (relative to those with higher BMIs) had higher FAS scores. These results support the notion that the FAS is measuring a common underlying construct across these national groups and respondent characteristics.