Abstract
This study aimed to confirm the hierarchical factor structure and the criterion validity of the Brief Mental Flexibility Questionnaire (BMFQ) in the South African context. Three hundred and eighty-five employees from a public institution in South Africa participated in the study. Confirmatory factor analysis affirmed the structural validity of the measure, comprising a general factor of mental flexibility and six distinct processes consistent with acceptance and commitment therapy (ACT): cognitive, affective, perceptual, attentional, motivational, and behavioral flexibility. Multiple regression analysis revealed differential predictive weights of these dimensions for general mental health, with cognitive flexibility as the primary predictor. Motivational flexibility emerged as the strongest predictor of adaptive performance. The BMFQ offers practitioners the ability to measure an individual's overall mental flexibility score alongside specific flexibility dimensions, enabling targeted interventions, employee comparisons, and organisational trend analysis.